Revealing mistake: When the weasels are at Eddie's apartment and Roger is handcuffed to Eddie, Roger runs under the bed and drags Eddie on the floor. As he pulls him you can clearly see a board with wheels under Eddie that is pulling him under the bed. (00:38:50)
Revealing mistake: When they show Heather Chandler in her casket in the funeral scene and everyone is praying, she's clearly breathing.
Revealing mistake: After her brother's death, there is a scene in which Alice starts practicing with her brother's nun-chuks. They never show the real actress doing the tricks; instead, they cut to an angle from behind her and show a double who has darker, shorter hair than the real actress and is a bit bigger. (00:56:45)
Revealing mistake: In the barber shop scene at the end of the film, Agent Anderson terrorises Deputy Sheriff Pell (who has a full head of hair) with a razor blade. Anderson throws him across the room, but the person being thrown across the room has a mostly bald head.
Revealing mistake: When Carol Anne has been hypnotized by the shrink, a hand breaks through the desk and throws a coffee mug through the mirror. You can briefly see the reflection of the plexi-glass protecting the actors behind the mirror as the mirror breaks.
Revealing mistake: When Dr. King checks on Mrs. Boynton, the dead woman opens her eyes by her own volition before her head rolls back. (00:45:00)
Revealing mistake: When Bernard throws his gun to the ground, the ground "wiggles". (01:09:15)