Ending Fatigue: Most of the plot is resolved in Spilt Milk, with most of the principal cast leaving Briarcliff. Two more episodes follow.
Ensemble Darkhorse: Pepper and Leigh Emerson. The former was popular enough to be brought back, making her the first character to appear in more than one season.
Fan Nickname: For the series itself, there's "American Horror Story: Assylum", due to the many, many ass shots in the show between the cane-ings and the clothing the prisoners wear, among other things.
Lana Banana, for Lana based on what Sister Jude said when they first met. Seeing as how Lana's the Woobie, it works well.
The show is also being called "American Whore Story", thanks to Dr. Arden's exclamation of "Whores get nothing!"
Foe Yay: Sister Mary Eunice has this with everyone, particularly Sister Jude.
Franchise Original Sin: "The Name Game", which worked so well partly because it was such a Big-Lipped Alligator Moment, paved the way for the less unexpected (and less plot relevant) musical numbers in Coven and Freak Show, which were, for the most part, objects of criticism in those seasons.
Sister Jude, especially after her massive Break the Haughty routine and the dirty details of her past come to light.
Les Yay: A small amount between Sister Mary Eunice and Lana. Interestingly, most of it is on Sister Mary Eunice's end, despite Lana being canonically lesbian.
Most Annoying Sound: The music that plays in the common room ("Dominique-inique-inique s'en allait tout simplement..."). Kit has attacked the record player more than once, just to get it to stop. It finally dies when Jude shatters the record, and is replaced with a much more tolerable jukebox assortment.
Most Wonderful Sound: The season ends with a flashback to Lana and Sister Jude speaking (rather civilly) as the former is about to leave the asylum (this is before she came back and ended up incarcerated for her trouble). The same song as above is playing, and after all the dreadful happenings the viewers have seen, it feels strangely peaceful.
Narm: Sister Mary Eunice is walking narm, what with her constant blubbering.
Dr. Arden puts lipstick on a statue of the virgin Mary, yells "whore" at it for a few minutes, then pushes it over.
Thredson: "Baby needs some colostrum." Doubles as Squick.
Dr. Arden's real name is Hans Gruber. It's kind of hard to establish tension when one of your characters' name sounds like a character from Die Hard.
The scene where Dr. Arden attempted to rape a prostitute would have been much more horrifying without the straight-faced delivery of the line "Show me your mossy bank."
Scenery Porn: The last two episodes After Lana and K It get out of Briarcliff start to look more like a sweeping Biopic rather than a Horror Finale.
Spoiled by the Format: The second season was announced to be running for 13 episodes even before the first had aired; however, this effectively spoils that a good amount of plot has yet to go, despite several story arcs being tied up by Episode 11/Spilt Milk.
Squick: Doctor Arden cuts into Kit's neck. An alien chip crawls out.
Sister Eunice stabs a patient to death with a pair of scissors.
And then Doctor Arden cuts off Shelley's legs. We thankful don't see this operation (our wonderful imaginations get to paint that picture for us), but we do see the aftermath and it... well, it's not pretty to say the least. Are we starting to see a pattern here concerning Doctor Arden?
They Wasted a Perfectly Good Plot: Early on, Dr. Arden uses a drug to stop Kit's heart, as part of his Batman Gambit to draw the aliens in. Later on, after Alma is committed to Briarcliff, there's a quick cut to her dead body. The explanation is that her heart stopped working with no explanation, and Kit is present for this explanation. Considering Alma's death took place in the vicinity of Dr. Arden's lab and the scene occurs soon after Kit visits Alma in Briarcliff, it seems safe to assume he snagged some of Dr. Arden's fake-death drugs from the lab he was already familiar with and used it to get Alma out of Briarcliff. But no, she just dies, and Kit goes on to marry another, anonymous character in the future.
Tough Act to Follow: Is widely considered the best season of the show to the point it is held as the gold standard for the others to live up to.