Answering Questions
In defense of the last episode - Beyond the Wall has gotten a lot of vitriol for the plot holes. And a good deal of that criticism was rightly earned because it requires a lot of after the fact rationalizations rather than naturally implied explanations within the context of the story. The biggest one is time compression. The gendry getting to the wall, to send the raven to Dany so she can get back to Jon part of the story was irritating and really can't be explained other than to say, suspend your disbelief. But there are a lot of other things in the episode that have raised questions or that people say make no sense. I thought I'd take a stab at some.
Why did the NK take out Viserion rather than Drogon first?
Simple answer would be a judgement call. He had a clearer shot at Viserion's heart and if he had wounded Drogon, Viserion was headed directly over his path and may have taken him out with Dragon breath.
Why did the NK wait so long to attack?
There have been a lot of practical explanations about how long it takes for a lake to freeze over. And those are plausible. We all know at this point that he has some kind of greensight. So what he knew, when he knew it and whether he planned to take a dragon are also plausible.
Was it too convenient for Benjen to come in at the last minute and why didn't he go with Jon?
Convenient yes. Although he could have been witnessing the entire skirmish and just been waiting for an opportunity to see if and when he was really needed. There are also plenty of reasons not to go with Jon. For one, there really was no time. Jon was freezing, he would have slowed down the riding time back to the wall and the wights were advancing. By staying behind he distracted them long enough for Jon to get away and get back faster.
Also, at this point, maybe he wanted to die. He was brought back for a purpose, and since he can no longer report to the 3 Eyed Raven Senior and the COTF since they are all dead, his purpose is fulfilled. Maybe he doesn't see any point in lingering in a world of endless winter as a half Walker. And we all know he can't pass beyond the wall.
Has Arya gone completely Carrot Top?
No. The note was enough to piss her off. And that was perfectly reasonable given her relationship to Sansa in the past. But I think most people missed the point of her last exchange with her sister. Whether Sansa knew it or not, she was actually playing the truth game with Arya. I interpreted Arya handing over the dagger as a symbolic gesture that she still trusted Sansa.
Did the NK go to Home Depot for the chains?
This one is a nitpick if I ever heard one. But some people are really annoyed by it. It seems perfectly reasonable and plausible to me that the army of the dead has been commandeering supplies at every outpost (including Hardhome). I assumed the chains could have been intended for the wights and walkers to climb the wall and/or pull chunks of it down with their wight giants. In any case there are numerous practical applications for them to have those at their disposal.
Did they retcon how to kill wights?
No. And another huge stupid complaint. In the past wights were killed by fire or really any other weapon, it just took longer. But thats not to say that dragonglass never worked on them in the past. It stand to reason if dragonglass works on a walker it will work on a wight and clearly it does so faster and more efficiently than a generic sword.
Sure these are rationalizations, but perfectly plausible. So if you are one to complain and quickly chalk it up to plot armor, I'd counter that by saying use your imagination.