Continuity mistake: When John Candy and Steve Martin are travelling from Jefferson City, Missouri to St. Louis they are seen crossing the Mississippi River to enter downtown St. Louis. This would not have been possible unless the bus driver overshot the entire city and ended up across the river in Illinois.
Continuity mistake: When Steve Martin gets off of the train in Chicago near the very end of the movie to search for John Candy in the depot, the part of his hair is on the opposite side (left) from where it normally is. There is no apparent wind blowing his hair - it looks neatly parted on the "wrong" side. When he enters the depot, the part in his hair is back to the "correct" side. (01:23:30)
Continuity mistake: When the boss puts his hands on the table at the beginning, between shots they go from being spread apart to very close together.
Continuity mistake: In the beginning when Neal's boss is done looking at Neal's work and is about to state his opinion, we see him holding his glasses in his hand while stretching it out. When it cuts from behind him the glasses are no longer in his hand but he has them hanging from his mouth. (00:01:30)
Continuity mistake: When Owen arrives at the hotel to meet Neal and Del to drive them to the train station, Owen is wearing gloves on both hands. As he introduces himself and shakes their hands, Owen's right hand is now bare even though there wasn't enough time to remove the glove. (00:33:55)
Continuity mistake: When Neal and Del are sitting at the counter eating breakfast at the Braidwood Hotel, talking about how they were robbed the night before, watch the plate of food in front of Neal. The food on the plate changes completely.
Continuity mistake: When Dell and Neal get dropped off to catch the train, there is a shot of the town they depart from. Later in the film, when their burned-out car is impounded, they catch a ride on a semi carrying dairy products, departing from the same town.
Continuity mistake: The size of the bed in Neal and Del's motel room changes overnight.
Continuity mistake: In the driving scene from St. Louis to Chicago, Del is having a hard time taking off his parka in the car. After he spins out of control his parka is half off when Neal says "It's getting hot in here, you should take your parka off." The next shot you see them driving away and Del's parka is on again. (00:33:15)
Continuity mistake: At the beginning, when Neil is racing Kevin Bacon for the taxi, he trips over the trunk and falls into the street, nearly being run over by a BMW. The car honks and pulls away. When the shot switches to show Kevin Bacon getting in the taxi, the car that almost hit Neil is now an Oldsmobile. (00:03:50)
Continuity mistake: Right after the close call going the wrong direction on the freeway and Steve Marting pulls his fingers out of the car's dashboard. The following shots show John Candy releases his grip of the steering. The top of the steering wheel has been completely push forward. All remaining shots of the car show the steering wheel in perfect alignment.
Continuity mistake: After leaving the El Rancho hotel. (when pulled over by the state police) Neil seams to find some new clothes, including a too small hunting hat, and scarf. On the walk home, Neil is carrying a large suit case, instead of his garment bag and brief case.