Continuity mistake: When Michael Douglas is listening to a "deposition" (which is really Glenn Close calling him names, etc.) using his ear phones in his new attic home (just before his wife comes up and finds him), the audio tape is not the same one as he was listening to minutes before in the car! The words are almost the same but the inflections are different.
Suggested correction: It is the same tape, although a mistake does remain - the tape when first being played in the attic is a few sentences before where the tape should start (without him rewinding it at all).
Continuity mistake: The water level was almost but not quite overflowing the brim of the tub when Michael Douglas is pushed in, and the faucet was still running, so there should have been more water on the floor. (01:52:25)
Visible crew/equipment: In the library, right after Dan breaks into Alex's apartment, a cameraman's reflection is visible in a window as a librarian pushes a cart past it.
Revealing mistake: In the final confrontation scene Glenn Close comes out of the bath tub and raises her arm, the scene cuts to the gun and when it returns to Glenn Close you can see the fabric of her dress has changed to a thicker one to accommodate and cover the squib needed for her gunshot wound. (01:54:05)
Revealing mistake: When Michael Douglas is listening to the "deposition" in his study, look closely at the background window. You can see Anne Archer's reflection in the glass, together with someone else (probably crew), just waiting for her cue to come in and surprise her husband.
Continuity mistake: The amount of blood on Dan's face, when Alex slits her wrist, keeps changing.
Visible crew/equipment: In the beginning of the movie as Michael Douglas runs to answer the phone someone has knocked the overhead lamp in his kitchen and set it swinging. (00:03:05)
Continuity mistake: There is a lot less blood on the knife after Glenn Close flings it than there was in the shot before when you see her fall. (01:51:50)
Continuity mistake: Fred Gwynne's pipe jumps from his hand to his mouth when he and Michael Douglas walk up the stairs to his office.
Visible crew/equipment: The shadow of a crew member goes across Michael Douglas' shirt as he's sitting on the couch reading in the beginning of the movie. (00:02:25)
Continuity mistake: In the scene in the tub, Glen Close's feet start out filthy, then they become clean as a whistle when she is flailing from her knees, then by the end of the scene they're disgusting again. (01:52:40)
Continuity mistake: As Michael Douglas listens to the answering machine, the green overhead lamp that is above the table in the beginning of the movie is gone. (00:22:20)
Visible crew/equipment: A shadow moves to the left of the refrigerator when Glenn Close says "I'm pregnant I'm gonna have our child." Michael Douglas doesn't move out of his position yet. (01:08:30)
Continuity mistake: At the start of the film we are introduced to Michael Douglas' family life. His wife is in the bathroom getting ready for their night out, Michael is sat on the couch reading and his daughter, Ellen, is sat on the chair watching cartoons. In one shot Ellen is sat on her own, but in the next shot their dog has magically appeared on her lap.
Continuity mistake: The amount of wine in the Michael Douglas' glass changes in the scene where he is talking to his daughter about rabbits. It fills up without being touched. (00:41:30)
Continuity mistake: (DVD only) In the new ending, when Alex attacks Beth at the family's home, Beth has bruises and a cast on her arm, obviously a result of the accident she was in a few days ago. In the original ending, presumably taking place within the same time frame, when the cops come to question Dan about Alex's death, Beth is fine - no bruises, no cast, she doesn't even look tired.
Continuity mistake: Dan plays the tape that Alex made in his car. He stops the tape when he gets home, and after he gives his daughter a pet rabbit, he goes to his den and puts the tape in the tape recorder and presses play - that's all; he doesn't rewind it - but what he hears is the same bit he heard in the car, which is wrong; the tape should have started play where it left off in the car.
Continuity mistake: When Alex goes to see Dan in his office, Dan in the first scene is sitting with uncrossed legs, then his legs are crossed, then uncrossed again.
Continuity mistake: In the party scene the people behind Stewart Pankin on the slow moving food line change it just a matter of seconds from shot to shot. (00:04:50)
Continuity mistake: In the very first scene we see Ann Archer pulling down a shade from afar with the curtains pulled to the side. Then we switch to her inside the apartment and see the curtains are already closed. (00:02:00)
