Factual error: When they're at the world series game, during the opening ceremonies, the scores of other ball games (NY vs PIT and DET vs NY) are showing in the background. There are no other games during a world series. (01:33:00)
Continuity mistake: 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.
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 mistake: 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.
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.
Continuity mistake: 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: During the tennis match, Sakamoto serves consecutive times to the same cross-court service box, the final time when it is triple-set point. The rules of tennis are that you switch sides between points.
Plot hole: When Sakamoto prepares to deliver his final serve in the tennis match, he declares, "Triple set point." Later we learn that he lost in three straight sets, so the statement should have been, "Triple match point."