Continuity mistake: In the first meeting between Derek and Lisa (elevator scene), the folders in Ali Larter's hands keep changing position between shots - look at the beige folder; its rubber band jumps between being on the left and being on the right multiple times. (00:05:30)
Continuity mistake: Derek at the beginning of the movie pranks Lisa pretending not to be who he is. During the cut happening across the "But don't tell him I said that, okay?" line, Lisa's hands switch position on the pile of folders she is holding; the hand on the bottom is the left first, then the right. (00:06:50)
Continuity mistake: The first time we see Derek back home from work he changes his son's diaper and then is with the wife, sitting on the floor. In the overhead shot the cups on the table point the handles in opposite directions, but at the cut Derek completes the action of pouring, and does it on cups oriented the exact same direction. (00:10:35)
Continuity mistake: In the first scene with Lisa acting as assistant for Derek, when they discuss the Gage rule about no spouse at the corporate party, Derek passes the pen twice from the same hand to the other. (00:12:10)
Continuity mistake: As Derek Charles hold his cup of coffee and engages in conversation, the cup changes hands several times between shots. (00:12:25)
Continuity mistake: Mrs. Charles visits her husband at work, and the tension is simmering. Lisa taps her on the shoulder after saying "It's nice to meet you, Sharon"; taps Beyoncé with the right hand, but in the reverse shot she's pulling back an outstretched left arm. (00:17:40)
Continuity mistake: When Lisa is lying on the floor after the chandelier falls and kills her, first shot she is facing right and then when they go back to her on an overhead shot she's facing left.
Continuity mistake: When Derek gets the New Year's e-mail from Lisa and he starts closing out the pictures, it shows the screen where he closes out all but two pictures. Then it goes to his face and back to the computer where it's gone back to three or four pictures.
Continuity mistake: When the detective talks to Lisa in her hospital bed, the pillow case changes from the pillow showing to it being completely covered and tucked in.
Continuity mistake: Sharon's shoes change from the time her and Derek walk into the house looking around to when they are in the attic.
Continuity mistake: During the fight at the end between Sharon and Lisa, when they are struggling over the phone, Sharon is to the right of Lisa. In the space of one second, the next shot shows them switching places, with Sharon left of Lisa.
