Continuity mistake: Jeffrey puts his glasses in his left pocket with his left hand and puts the magazine down. But when they show him again the glasses are back in his right hand and paper in left. (00:49:20)
Continuity mistake: When Jeffrey comes out on the balcony through the window it shuts behind him. When he pulls Celeste over the railing the window is now wide open. (00:58:25 - 00:59:15)
Continuity mistake: When Celeste is watching her meltdown on TV, the dialogue is different from the actual live scene. Most notably, the taped version shown on the TV has Celeste saying "Lori, trust me," which is never said throughout the actual live scene.
Continuity mistake: In the scene in the Chinese restaurant where Celeste, Lori and Jeffrey are discussing the brain transplant, Nurse Nan walks in. When Jeffrey comments he doesn't have any tools, Nurse Nan holds up the saw and mask and says "Voila." In the next shot, her hands are down by her side.
Continuity mistake: When Sally Field asks which apartment, she's told 2D. She goes to apartment 2A, and finds the guy she's looking for.