Character mistake: When Lana and Kit are speaking in the cafe, the window behind them contains a spelling mistake. The window reads "Bolyston Cafe" when it should say "Boylston Cafe." (00:31:45)
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.
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.
Suggested correction: Tate's victims from the school shooting are ghosts who can move between different locations. There's nothing to suggest that the ghost of the Black Dahlia isn't merely choosing to be in the Murder House rather than being tied to it. The same goes for Vivien and Ben, since Violet is going to stay in the house, so might they.
Factual error: The same 1990-1991 Buick Lesabre seen in a previous episode appears in the background of the scene. The season is set in 1981, roughly a decade before this car would've been in production. (00:11:01)
Bad Fortune - S11-E5
Factual error: This episode includes a 1990-1991 Buick Lesabre as a background vehicle, while the season is set in 1981. (00:02:10)
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)
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: When Elsa reveals her prosthetic legs to Dot and Bette, they are two inches below her kneecaps, when in prior episodes they were just beneath.
Blood Bath - S4-E8
Revealing mistake: Elsa's legs are supposed to be wooden prosthetics, but when she walks away from Ethel, who's holding a gun at her, it cuts to a shot of Jessica's calves which bend slightly as she walks. (00:00:14)
Piggy Piggy - S1-E6
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.
Continuity mistake: While Brooke is on the floor being tormented by Montana, a rug next to Brooke disappears and moves to another part of the room as the scene cuts.
Mr. Jingles - S9-E2
Continuity mistake: Xavier holds his flashlight low when he turns to shine it on the camp light that just went out, but the next shows him holding the flashlight higher, and closer to his ear.
Mr. Jingles - S9-E2
Continuity mistake: After Blake says, "Gay for pay, baby.", his left hand is up by his mouth, then by his side in the next quick cut.
Camp Redwood - S9-E1
Continuity mistake: After Trevor scans the woods with the flashlight from the porch, he lowers it to his side, but the next shot of him from the woods shows him still holding the flashlight up and his arm extended.
Camp Redwood - S9-E1
Continuity mistake: As Margaret briefs the counselors on the rules, Xavier is positioned to the right of Ray's right shoulder, but when the shot is of the back view of the group facing Margaret, Xavier is now directly behind Ray.
Camp Redwood - S9-E1
Continuity mistake: Margaret plants the axe into the chopping block, but in the next shot when she greets the new counselors, the axe is now leaning against the chopping block.
Camp Redwood - S9-E1
Continuity mistake: The view of Ed is through the right front of the van's windshield when he says, "Did you say Redwood?", then the next shot of him shows he is further away from the van and not near the windshield.
Camp Redwood - S9-E1
Revealing mistake: When Brooke parks her car, set lights are reflected in the driver's side door when she opens it to exit the vehicle.
Camp Redwood - S9-E1
Continuity mistake: As Brooke explains to the group she is planning to be a veterinary assistant, Montana turns her head to the left twice as the scene cuts.
Camp Redwood - S9-E1
Continuity mistake: In the scene of the aerobics studio lobby when the group decides to leave for Camp Redwood, Ray is shown getting up and standing twice.