Other mistake: In scene where Celeste follows her niece Lori to Jeffrey's Apt, she is trying to fool the Doorman and says "He's in 11-A, right?" He replies "2D." Later, when Jeffrey catches Celeste on the fir escape and let's her out via his front door, the apt door is marked "2A."
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.