Goof (continuity error): Frances Conroy ("Old" Moira O'Hara) is right-eye dominant. Many times you can see that she, as Moira, is focusing on the object she's looking at using her "blind" right eye instead of her left eye.
Goof (continuity error): Vivian gives Ben a long cut on the left arm after she catches him committing adultery. But every time we see his arm during the rest of the show, there is no scar.
Goof (continuity error): When Ben is pleasuring himself near the window after seeing Moira, the curtains are closed at first, but when the camera cuts to his head the curtains are open.
Goof (factual errors): When Ben goes to light the fireplace, he turns the gas valve clockwise. Gas valves, as with all valves, open counter clockwise.
Goof (continuity error): When Violet goes to set the cupcake down outside her door, you can see icing on the rim of the plate. However, when the camera jumps, the plate is clean.
Goof (anachronisms): The beginning opens to the 5th Dimension singing "The Age of Aquarius" with the date 1968 on the screen. But that album and single was not released by the 5th Dimension until 1969. Before then, theater cast members sang it for the "Hair" musicals onstage.
Goof (anachronisms): In the clips of Rowan And Martin's Laugh-In, Tennessee Ernie Ford was shown talking to Goldie Hawn in a skit but he did not appear on the show until November 1969. It would have been impossible to have this playing on TV a year before it aired.
Goof (crew or equipment visible): SPOILER: When Ben heads back into the house after Hayden is attacked, you can make out the shape of knee pads under his trousers.
Goof (anachronisms): Nora Montgomery receives the "eye for an eye" phone call. The caller hangs up and we hear a dial tone. However, the time period is supposed to be the 1920's, dial tone was not introduced until the 1940's.
Goof (continuity error): When Tate is surrounded by the SWAT team, as he gets the gun (no shots have been fired) you can see blood on Tates neck.
Goof (anachronisms): During the opening scene in 1994, the book cart used to barricade the library door holds "The Children's Blizzard" which was first published in 2004.
Goof (continuity error): SPOILER: The wounds given to some of the students during the school shooting are inconsistent with how they appear as ghosts. Specifically Kyle Greenwell (the jock), shown to have a small, single gunshot wound to the forehead as a ghost, is shown being shot with a shotgun.
Goof (anachronisms): Nora Montgomery, a ghost who died in 1926, is seen wearing bright red nail polish in a scene. Nail varnish like that did not yet exist. It was only invented in 1934 by Max Factor. At the time Nora lived women did not put polish on their nails at all; they were only oiled and creamed.
Goof (factual errors): When Tate is picking up the rubber suit from the garbage can, the garbage can is located outside the gates of the house. However, the ghosts aren't allowed to go past the gates.
Goof (continuity error): (at around 8 mins) As Constance reviews the crime scene pictures of Travis, his eyes are open in one picture and closed in the other. Even though it is not unheard of for someone at the crime scene to close the eyes of a deceased individual it would not be done in the midst of the crime scene photos being taken.
Goof (continuity error): Violet sits at the kitchen table, clearly smoking Marlboro Gold 72's, looking pretty glum. Yet, when Constance enters, she pulls an American Spirit cigarette (known for the printed eagle above the filter) from the pack and lights up.
Goof (anachronisms): Young Tate is wearing a pair of "Shaq Attaq" sneakers in 1984. Shaq wasn't drafted into the NBA until 8 years later, making him 12 years old in 1984.
Goof (factual errors): Under canon law, an exorcism could not have taken place the same day as Jed's admittance.
Goof (factual errors): Dr. Arden quotes Matthew 7:3 to the Monsignor. The language of the verse is from the NIV version, which wasn't published until 1978. This scene takes place in 1964.
Goof (errors made by characters, possibly deliberate errors by the filmmakers): Joseph Fiennes, though portraying a catholic priest, crosses himself like an orthodox priest when in the chapel with Ian McShane.
Goof (continuity error): As Sister Mary Eunice is falling from the stairwell in the atrium, her legs change positions between shots.
Goof (continuity error): When Madame LaLaurie is first applying blood to her face, some of it is applied above her upper lip and below her bottom lip. As Louis enters the bedroom, that blood has disappeared.
Goof (audio/visual unsynchronized): In the last scene, the sound of a horn is heard. It is falling in pitch, but the taxi cab is approaching the two women. The physics of the Doppler Effect dictate that the pitch of the horn should rise as it approaches the women, and fall as it drives away.
Goof (errors made by characters, possibly deliberate errors by the filmmakers): Hank calls Cordelia by Misty's name. Misty is also in the shot, but Hank is clearly talking to Cordelia directly.