Revealing mistake: When Tristan Duffy is sitting on the chair and looking through guys on a dating website to lure to the hotel, you can see he is just looking at photos in the gallery on the iPhone he's using. (has all the gallery interfacing) yet he clicks the screen and it makes a noise like he was on an actual dating app. (01:07:54)
Visible crew/equipment: In the scene where Lana Winters imagines receiving an award for her expose while in line for her medication, her mic pack is visible as she steps up to accept it. It is not visible in the high angle long shot before she gives her speech. (00:17:15)
Factual error: All the survivors save Ms Venables and Mead die from eating apples injected with snake venom. The show is confusing venom with poison. Venom must be injected into the bloodstream to be dangerous. Eating venom is harmless to humans. Unless all of the survivors had stomach ulcers, none of them should have shown any ill effects, nor should they have died.
Deliberate mistake: After Elsa kicks Bette and Dot off the stage, Elsa looks at the sheet of music on the stand and you see the name of the song 'Criminal' and it also states it's by Fiona Apple which is true, but this season is set in 1952, and Criminal wasn't released until 1996.
Plot hole: It's been established that if you die on the property, you remain as a ghost for all of eternity. However, in Season 8, Moira's bones are retrieved and buried in a cemetery so that her ghost can escape and join her mother. However not all the ghost's bones are buried on the property, we know for sure that the Black Dahlia was not buried on the property and it's not likely Tate, Vivian, Ben or some of the others are buried on the property as well so they should not be tied to the house.
Revealing mistake: As Iris is telling Detective Lowe about Mr. March when he built the hotel (with the flashback) in the close up shot of the police officer holding the handkerchief, you can see The Dead victim's stomach moving as the actor is breathing, although he's supposed to be dead. (01:01:35)
Continuity mistake: The people that Tate murders at school have different wound patterns. Episode 5 they say what Tate did to them, episode 6 shows the attack. Episode 5 the goth girl says Tate asked her if she believed in God before shooting her - episode 6 he asked her nothing, instead just shot her. Episode 5, the guy in the letterman jacket illustrates his wound to be a single round to the head - episode 6 he shoots the letterman with a shotgun in the chest, not a handgun to the head. Episode 5 the cheerleader shows no apparent wounds of being shot - episode 6 Tate shoots her in the face with a shotgun.