1. Why didn't Cersei blowing up the Great Sept of Baelor in the Season 6 finale have a bigger impact in the Seven Kingdoms?
In the final episode of Season 6, Cersei Lannister overcame her enemies in King's Landing by tricking them into all gathering in one place - the Great Sept of Baelor - and then blowing it sky high with titanic amounts of wildfire. The High Septon, Ser Kevan Lannister, Ser Lancel Lannister, Lord Mace Tyrell, Queen Margaery Tyrell and Ser Loras Tyrell were all incinerated. King Tommen Lannister, distraught at the deaths of so many innocents (including his wife), killed himself shortly afterwards). In the aftermath Cersei crowned herself Queen of the Seven Kingdoms and took the Iron Throne for herself, despite having no real claim to it.
This is an easy decision to criticise: we know from Seasons 5 and 6 that the wanton slaughter of the War of the Five Kings has driven millions of Westerosi back into the worship of the Faith of the Seven. The new High Septon comes to power from being genuinely a man of peace, faith and vision (and also a fundamentalist martinet out to slaughter all enemies of the Faith, but still). Cersei blowing him and most of the Faith sky-high might be satisfying in the short term, but realistically it would enrage millions of followers of the Faith, lead to her being denounced as a monster and usurper by septons and septs up and down Westeros and would drive lots of lords from her cause. Because she also murders her uncle, cousin and daughter-by-marriage, she would also be dubbed a kinslayer, a horrendous curse in the Seven Kingdoms. We don't see any of this in the show.
However, Season 7 does suggest that Cersei's grip on power is very shaky (Jaime says as much several times). The Lannister army and the Westerlands remain Cersei's primary support and pretty much everyone else has already sided against her. The show doesn't have any reason to delve into the little people living in the Crownlands and Stormlands (the other regions more or less loyal to King's Landing at this point) so their viewpoint is unknown, and we don't know how many other people decamped from her side after the massacre. Season 7 does show other lords being wooed back to Cersei's side once the dust settles and she's still alive, so political expediency likely won over a lot of support lost in the Septocalypse.
"Now I'm king, let's go plane some wood! Bring me my lathe!"
2. How did Euron Greyjoy build a new fleet so fast?
Back in Season 6, Episode 5 (The Door), Euron Greyjoy wins the Kingsmoot to be crowned King of the Iron Islands, only to find that Yara and Theon have fled with most of the ironborn fleet. They wind up in Meereen and swear fealty to Daenerys. Euron pledges to build a new fleet, vowing to have a thousand ships to take into battle.
In Season 7, Episode 1 (Dragonstone) this fleet shows up at King's Landing to join forces with the Lannisters, to Cersei's delight and Jaime's disquiet, and is deployed in the very next episode to destroy most of Yara and Theon's forces.
With this one, I think we have to assume that, despite indications to the contrary, Yara and Theon only took a small portion of the total ironborn fleet to Meereen and Euron thus inherited an already-substantial force which he later augmented with a relatively small number of new ships - built or perhaps seized on the Summer Sea and in the Stepstones during the long journey around Westeros - rather than that he built hundreds upon hundreds of pretty large warships from scratch and sailed them thousands of miles right around the coast of Westeros in the space of a few months.
"How did you get here so fast?"
"We opened a warren."
"Isn't that a different fantasy series?"
At the end of Season 7, Episode 1, Daenerys lands on Dragonstone with a substantial force: 100,000+ Dothraki and their horses, thousands of Unsullied (originally 6,000 but many were lost in Meereen) and a fleet of at least 350 warships and transports, not to mention three huge dragons. Due to the need to carry both Dothraki and their horses, this fleet would need to actually be considerably larger, or used in ferrying operations (perhaps only some Dothraki went with Dany and the rest rode to Pentos and were ferried across the Narrow Sea in shifts).
Dragonstone sits at the mouth of Blackwater Bay, where it meets the Narrow Sea, and is highly defensible. The only way in or out of the Bay is the Gullet, a narrow stretch of water to the south of the island (the channel to the north, between the islands of Dragonstone and Driftmark and the mainland of Crackclaw Point, is apparently too rocky and too narrow for large fleets to traverse). In the novels, the Gullet is about sixty miles wide; however, due to the fact that TV Westeros is significantly smaller than Book Westeros, the TV version of the channel must be significantly smaller and thus easier to blockade.
However, in Season 7, Episode 2 (Stormborn) Euron's fleet is able to leave Blackwater Bay and pursue and destroy Yara and Theon's fleet as it sails down the coast to pick up the Dornish army. It would seem to be strategic folly for Daenerys to leave Blackwater Bay unguarded; even if Dany's fleet is half or less the size of Euron's armada, it should be still be possible to deploy her dragons and sink the fleet. The only assumption I can make here is the Daenerys did not bother to scout King's Landing and didn't know that Euron's fleet was present, and most or all of Dany's military fleet was sent to Dorne and the ships that were left behind were not sufficient to challenge Euron. Dany may also have chosen not to deploy the dragons and risk them in battle at this time.
To be honest, none of this really washes. Dany has enough competent military advisors to know that scouting King's Landing to learn the disposition of Cersei's forces (particularly her navy; it's worth remembering, unlike in the books, the Royal Fleet has not been destroyed or stolen in the TV series) is essential, and the geography makes impossible for even a small detachment of Euron's fleet to simply sneak past Dragonstone without anyone noticing.
"Good thing the Tyrells don't have the biggest army in Westeros or anything!" *fistbump*
4. The battles of Casterly Rock and Highgarden don't make sense.
They don't, and this plot point really can't be salvaged. Nevertheless, we'll make an attempt.
In the case of the attack on Casterly Rock, the Unsullied sail from Dragonstone to the Westerlands, disembark and besiege the castle. Grey Worm leads an infiltration of the fortress, opens the gates and the Unsullied take the castle with relative ease: the Lannisters have abandoned the fortress. Euron's fleet then closes the trap on the Unsullied and destroys their fleet, blockading them by sea.
This plan has a lot of holes, most notably allowing your enemy to gain control of an impregnable, well-stocked fortress on the mainland. A great house losing their stronghold is also always seen as a titanic display of weakness: Robb losing Winterfell to the Greyjoys in Season 2 is enough to spark his decision to return home in Season 3 and we know how that turned out.
We can assume that Grey Worm and his fleet left Dragonstone before the ironborn/Dornish armada. This explains why Euron simply didn't destroy them at sea, they were too far behind and didn't catch up until the Unsullied had already taken Casterly Rock. We can also assume that the Lannister plan to turn and besiege Casterly Rock didn't happen; given that the Unsullied army is back at King's Landing in the Season 7 finale, it's likely the Unsullied sortied ASAP and headed north and east through the Riverlands (where no effective resistance is left) before circling back down towards the capital, preventing the Lannisters (too far to the south at Highgarden) from intercepting them.
Unfortunately, whilst the Casterly Rock campaign can be (sort of, if you squint a bit) salvaged, Highgarden cannot with some major logic leaps.
We know from Season 2 (and not even touching the books, with their much more detailed military numbers) that King Renly Baratheon commanded an army of over one hundred thousand troops, most of them from the Reach. Ser Loras Tyrell is noted as an incredibly impressive warrior (even if we never see any evidence of it on the show) and Lord Randyll Tarly, a Tyrell loyalist, is noted as an impressive battlefield commander. The immense power of House Tyrell later on, with the Queen of Thorns and Margaery Tyrell able to use the threat of House Tyrell withdrawing its support for the Lannisters to force concessions even from Tywin Lannister, is reiterated quite a few times.
But in Season 7, Episode 3 (The Queen's Justice), the considerably smaller (and battle-worn) Lannister army routs the Tyrell host and seizes Highgarden. The only nod to the Tyrell's previously-established military superiority is Jaime saying that the Tyrells aren't great fighters, which feels a bit unconvincing. The Lannister host was originally 60,000 strong (in Season 1, Episode 7). Half of this army routs at the Whispering Wood. Another Lannister host is raised, but this is destroyed at Oxcross in Season 2, Episode 4 (Garden of Bones). This leaves the main Lannister army (the one Tywin commands from Harrenhal in Season 2 and, allied to the Tyrells, saves King's Landing at the Blackwater) at only 30,000 in strength. We can assume that Jaime eventually rallies some of the survivors of the other armies and increases this in number, but at best the Lannister army is half the size of the Tyrell one.
There are several equalising factors. The most notable is when Lord Tarly and several other Reach lords betray Highgarden for Cersei. This would both reduce the Tyrell strength and increase the Lannister's. We can also assume that some other lords would stand aside and not take the field rather than choose sides. This could reduce the Tyrell strength significantly, although still not enough to result in a massacre rather than a pitched battle which would reduce the Lannister strength quite considerably even in victory. The speed of the Lannister advance and their decision to strip Casterly Rock bare to support the attack may make a surprise attack plausible, but whichever way you cut it, this is a massive stretch of credibility.
5. How did Daenerys's army take Jaime's by surprise?
At the end of Season 7, Episode 4 (The Spoils of War), the Targaryen army, backed up by dragonfire, catches the Lannister-Tarly host strung out along the Blackwater and utterly destroys it in a spectacular display of Daenerys's power. However, some have questioned if it is plausible that Dany's forces could arrive undetected. In the medieval period it was very rare for armies to catch one another by surprise: large armies moved very slowly and single outriders and scouts could easily stumble across an enemy force and retreat to give warning of their approach.
This point is debatable. First of all, we need to locate the battlefield. We know it's on the Blackwater and we know that leading elements of the convoy have already reached King's Landing. Jaime wants the rear of the convoy through the gates before nightfall, so assuming that scene is near dawn (which makes sense, the convoy is breaking camp and getting ready to move) King's Landing is probably no more than thirty miles away.
Dany's ground force in this battle is exclusively made up of Dothraki, a fast-moving cavalry army. Although this army would move very quickly compared to one made of footsoldiers, it would still be slower than individual scouts and outriders. It is possible that Jaime did not send out scouts, or if he did he kept these oriented to the south, fearing an attack by Tyrell loyalists. However, given Jaime's superior generalmanship, this seems unlikely. More possible is that the Lannister scouts were spotted and killed by the Dothraki (or dragons) before giving warning.
More problematic is how the Dothrkai landed on the mainland unimpeded. We'll assume that not all 100,000+ Dothraki were sent and a much smaller force landed, one that could be sailed across Blackwater Bay and landed south of the Blackwater Rush in one go, quite quickly. The southern banks of the Blackwater are heavily forested, which is not ideal cavalry country, but we can assume that over the course of a few days the Dothraki were able to land, cut their way through the woods and then circle around to attack the Lannister force in the nick of time before it escaped. This does all suggest that the entire ironborn fleet went west with Euron and the royal fleet remains AWOL, leaving King's Landing and the approaching sealanes completely defenceless, which is a bit weird, but okay.
6. Operation Wightcatcher: like, how?
The sixth episode of GoT's seventh season features the Westerosi All-Star Rumble Squad (Jon Snow, Tormund Giantsbane, Jorah Mormont, Thoros of Myr, Beric Dondarrion, Sandor Clegane, Gendry Boatrower and a conveniently vague number of extras) being formed to capture a wight and use it to convince Cersei Lannister to agree to a truce so everyone in the Seven Kingdoms can team up against the Night King and his army of White Walkers. We'll gloss over the fact that whoever came up with this plan was clearly tripping balls and focus on how the operation unfolds.
Our heroes set out from Eastwatch-by-the-Sea and head north for a vague distance, but clearly hours/many miles. As they head north, they engage in #bants and learn more about each other as people, whilst fighting off a zombie polar bear (potentially some kind of Lost reference, I don't know). Eventually, they capture a wight and are then attacked by the entire goddamned Army of Darkness. Gendry runs off to the Wall to get help.
At this point logic checks out and some very weird things happen. Gendry runs back to the Wall, apparently in just a few hours, and sends off an emergency raven from Eastwatch to Dragonstone. Daenerys heeds the call and rockets north with her dragons to supply a dramatic rescue. During all of this, our heroes are stuck on a frozen lake surrounded by extras from The Walking Dead.
Subquestion 1: How far can ravens fly in one day?
The answer seems to be that no-one really knows. However, the greatest distance covered in one day by a racing pigeon appears to be 750 miles, from Lulea to Malmo in Sweden, and 720 miles, from Nantes in France to Fraserburgh in Scotland, both done in about fourteen hours. That puts their speed at approximately 50-55mph.
Dragonstone is approximately 1,500 miles south of Eastwatch in a straight line using the book maps, but recalling that TV Westeros is smaller than Book Westeros, we can assume that it's certainly less than 1,400 miles. Ergo, a raven from Eastwatch could plausibly reach Dragonstone in two days (possibly less if there is a relay system with the raven resting at another castle along the way and a maester relaying the message to a fresh raven).
Subquestion 2: How far can dragons fly in one day?
Assuming Daenerys sorties immediately, how fast could her dragons get back to the scene of the action? Obviously dragons don't exist, so this is a bit more open to argument, and of course that argument ends only one way: they fly at the speed of plot.
More satisfyingly, we know from A Dance with Dragons that Drogon can traverse half the width of Meereen in a few seconds and Meereen is one of the largest cities in the ASoIaF world. More specifically, in The Rogue Prince it is said that Syrax and Caraxes could fly the distance from Dragonstone to King's Landing - about 400 miles in a straight line in the books so less in the TV show - and back again in less than a day. That suggests that the dragons can at least match the ravens/racing pigeons in velocity.
Given a dragon's much greater strength, wingspan and the fact that they are inherently magical (because to really exist a dragon would need a wing/body ratio far out of keeping with most depictions of the creatures), it is not unreasonable to suggest that they are twice as fast as a pigeon, which would indicate that the dragons could reach the site of the battle in as little as one day after leaving Dragonstone.
Thus, the total time that Team Snow spent on the island would be around three days. This is not completely implausible and is also backed up by the need for the lake to refreeze: at minus 20 degrees, it takes approximately three days to form ten inches of ice, which is what will be needed to support the weight of individual wights crossing the ice.
Ergo, and maybe surprisingly, this one is actually pretty plausible.
7. Is it plausible that the Night King could kill Viserion?
Only if the Night King is Superman.
Although let's back that up a bit. The Night King throws an ice spear which punctures Viserion's throat mid-fireblast and causes him to partially explode before plummeting out of the sky and crashing through the ice to his icy death.
I had some satisfaction from predicting very early in my time on Westeros.org (a dozen years ago now) that the only thing that could pose a threat to Dany's dragons was an AA missile launcher. I just wasn't quite expecting this theory to turn out to be so accurate.
The Ringer called in Olympic javelin thrower Kara Winger to analyse the Night King's form. Her analysis was that the Night King did not put sufficient force into the throw for it to be convincing on its own merits, or to put it another way, despite some good aiming technique the Night King basically hurled the ice javelin a bit off-handedly. The javelin travelled easily more than 100 metres (the world record javelin throw is 103 metres, achieved by Uwe Hohn at the 1984 Olympics) and was still going fast enough and with enough force to kill Viserion. Even given that Viserion was flying at high speed towards the javelin (so the dragon's own velocity played a role in the blow being fatal), this was a hugely impressive feat.
To put it another way, the Night King is basically Superman. The White Walkers seem to have superior strength to normal humans anyway, and the Night King seems to be an order of magnitude above that. If the Night King ever gets into a swordfight with someone (which is entirely possible), he'd probably be able to split them in half with a flick of his wrist. I wouldn't even put Gregor up against him.
8. Where the hell did the wights get those chains from and why did they carry them hundreds of miles?
This is actually a more involved question, leading into both why the White Walkers took forever to get from Hardhome to Eastwatch (a trivially tiny distance compared to the distances traversed by everyone else this season alone) and what the Night King's original plan was to get through the Wall, given that the book-maguffin that everyone expects the to bring the Wall down (the Horn of Joramun) effectively does not exist in the TV show.
In order for this all to make sense we need to rewind. The Night King seems to be preternaturally aware of supernatural stuff going on in the world. He knows when Bran is spying on him and can disperse his ravens as well as "marking him" through their shared visions. This may be a result of the obsidian sword being plunged into him near a heart tree, and may have given him some of Bran's powers. As such, it is not implausible that the Night King has sensed the return of the dragons and knows they are (relatively) close by on Dragonstone. He also knows that dragons are magical creatures and may be able to overcome the Wall's own magical defences. Those defences seem to prevent both the White Walkers and wights from climbing, passing through, under or over the Wall (although they can be carried through and reanimate on the other side), so he needs some more firepower.
So if his plan is to bag a dragon, he knows he'll need chains. Hardhome, being a port with ships tying up, likely has a ready supply of chains so he makes sure his minions grab those (he might have been thinking to restrain a dragon rather than having to get it out of a frozen ice lake, but he can adapt his plans on the fly, which is why he's king). Then it's just a question of waiting for Jon to return and try something which he can use to lure the dragons in, kill one and turn it.
It's a bit of a stretch (cough), because it requires the Night King (whom we don't have much solid info on in terms of abilities) to have some pretty advanced magical knowledge, but it's not impossible.
Subquestion 1: Why kill Viserion and not Drogon?
It's possible that if the Night King killed Drogon - and thus Daenerys - the other two dragons would go psycho and burn the Night King before he can get a second ice spear ready. Bringing down Viserion and making Team Dany flee therefore makes more tactical sense. The Night King is playing the long game here and the most important thing for him is securing a Wall-destroying weapon, not wiping everyone out at this point. Plenty of time for that later.
Convinced? No, me neither. Still, you can kind of make a half-hearted nod at there being an explanation, which also encompasses why the White Walkers didn't make a beeline for Eastwatch straight from Hardhome.
Why don't the White Walkers advance straight on the Wall after securing Viserion, since weeks must elapse whilst Jon and Daenerys are visiting King's Landing, planning on Dragonstone and heading back to Winterfell? Er, pass.
Feels like another line is...missing.
9. Why does Daenerys think she's infertile?
Because of Mirri Maz Duur's prophecy, that she is effectively infertile and cannot bear a living child until the sun rises in the west and sets in the east, the mountains blow in the wind like leaves and the sea dries up etc.
Look at this scene from Season 1:
Oh, David Benioff and D.B. Weiss edited the line out because...reasons. Okay, we'll assume that Mirri Maz Duur told Daenerys she was infertile off-camera. Or something.
10. Can you really get to Winterfell from King's Landing in two weeks?
No. The show firmly established that it's a one-month ride from King's Landing to Winterfell (and more like two months in the books) in the very first episode of the entire series. The Dothraki might be able to shave a few days off that since they are so rad, but halving the time is implausible. It would require them to do almost 100 miles a day, every day, through winter weather, continuously for two weeks and the Dothraki are not particularly equipped for long winter rides.
The wording of the scene is a little anomalous; it might be that they were intending to land the Dothraki further up the coast, so they'd have a bit less to ride than the full distance from King's Landing, before the boats return to pick up Dany and Jon.
11. Do a million people live in King's Landing?
In the books the population of King's Landing, when it's swollen with refugees and soldiers during the events of A Storm of Swords, is said to be half a million. Logically, during peacetime, the population would probably be more like 350,000 to 400,000. That's still on the high side for a medieval city, but hey, it's fantasy.
Crucially, the line giving the population of King's Landing in the books is missing from the show, so the population being a million is, with the internal consistency of the show, not impossible. It seems a bit ludicrous, especially given how small the city appears (a hold-over from them filming in Dubrovnik, Croatia, and basing the city on Dubrovnik's Old Town, which is very small indeed), but perhaps the official population of the city includes some surrounding farms, towns and villages and Tyrion is rounding up a fair bit.
12. Do more people live in King's Landing than the North?
No. Robb Stark took 20,000 men south when he went to fight the Lannisters, and Jon and Sansa have managed to raise about another 6-10,000 men for their conflicts. Given the vagaries of medieval supply and army size, an army of around 30,000 would require a minimum supporting population of about three million (in the medieval period the ratio of soldiers to the rest of the population was about 1-99). Ergo, the North cannot have a population as small as one million. It should be noted that the North, even given the smaller size of Show Westeros, would still swallow three million people scattered across its area and still be quite sparsely populated.
So there you have it, some of the issues with Season 7 aren't really problems, others are hand-waveable and others actually really are just nonsense. Let's now look forwards to Season 8 when we can do this all over again.