Factual error: When Jimmy hot-wires the Lotus for the last time, he touches a red wire to a black one, the starter engages and the engine starts. Then he twists the two wires together. This would result in the starter running constantly, overheating it, and burning it out. A competent car thief would know never to do that.

Continuity: When Jimmy goes into the big house, he does not close the door, but while he is dancing you can see behind him the door open/close/open.

Plot hole: Jim Belushi impersonates Charles Grodin after stealing his identity. During the film he wears his clothes, including a business suit which somehow fits perfectly despite the fact that they have completely different body sizes.

Continuity: At the end of the film, Jim Belushi dresses as his mother to trick the warden and enter the prison. After he enters, he changes clothes and reemerges as himself. The bright red nail polish he had on is now completely removed from all his fingernails, yet at the same time he forgets to wipe his lipstick.

Continuity: When Charles Grodin is on the payphone at the airport his Filofax is open. After he leaves and Jim Belushi finds it, it's suddenly closed.

Factual error: The World Series tickets Jimmy has are printed on thin paper. When the real Spencer grabs them they fold. Normal World Series tickets are almost as thick as cardboard and commemorative looking. The tickets in the movie do not even look like normal game tickets.

Plot hole: When Jimmy and Spencer are being chased by the cops at the stadium, Jimmy uses a credit card to jimmy a door knob latch. However, the knob isn't locked, because it has no key hole. The dead bolt above the door handle is the one locked, and no credit card is going to jimmy a deadbolt.