Continuity mistake: As Dalton stands inside the bank vault staring at the cash, the scene jumps from a wide, distant shot, to medium, to close-in, just outside the cage. Another robber stands just outside and between jumps his gun position shifts from relaxed to raised to relaxed again.
Revealing mistake: When Detective Frazier enters the bank and tries to get the jump on Dalton Russell, they get into a struggle and fall down the stairs. As they fall down, look at Detective Frazier's head. It is supposed to be bald, but it suddenly has a full head of hair. It's quite obviously a stunt double.
Deliberate mistake: At 1:44:31 a close-up of a bank safe deposit records document shows box sizes that don't match the sizes of the boxes themselves shown at 0:58:41 and 1:55:21. The document shows box 378=3x10, 379=5x5, 384=5x5, 388=3x10, 396=5x5 but the boxes themselves appear to be 378=5x5, 379=5x5, 384=3x10, 388=3x10, 396=10x10.
Revealing mistake: During the final conversation between Detective Frazier and Arthur Case, Frazier holds up his hand with the ring on his middle finger. It is pretty obvious that the hand was inserted into the scene in post production; the hand doesn't move in a natural way and simply looks out of place.
Continuity mistake: Near the end, when Jodie Foster barges in to see Christopher Plummer at the barber, she has a tote bag. She sits in an empty barber chair and places the bag on the floor before speaking to Plummer. As she rises to leave, she picks up the bag, but when the shot cuts to her just as she walked out the door, she is no longer carrying it. Both hands are clearly visible as she buttons her jacket, and the bag is not in either hand, nor is it slung over her wrist or arm. It is simply not there. This particular shot may only be visible in the theatrical and widescreen DVD versions, and not in an edited and "pan and scan" format.