Continuity mistake: When Jack and the Duke are in the restaurant car of the first train, Jack is eating a chicken leg in one shot. In the middle of a sentence he changes to eating jelly and ice cream, which he finishes. In the very next shot his bowl is full of jelly and ice cream again.
Continuity mistake: At the beginning of the movie when Tony and Joey (Morons #1 and 2) meet Jack Walsh at the car rental desk, Tony writes a phone number on a packet of matches in pencil. Near the end of the movie when Jack Walsh fishes this pack of matches from his pocket, the phone number is written in pen.
Continuity mistake: When Jonathan (The Duke) rescues Jack from the river, he holds out a long pole with a fork in it. When Jack pulls himself out of the river, the pole is straight and has no fork.
Continuity mistake: When Jack and Jonathan are sitting in the carriage on the first train, Jack holds a pad in his left hand and a pen in his right. He then lights a cigarette. In a sequence of shots, his right hand is holding the pen, the cigarette or both together. At no time does he change either item to his left hand.
Factual error: When Jack is trying to buy the bus tickets, the bus company employee tells him that his credit card was cancelled. Credit card companies do not divulge that type of information, they simply indicate whether the requested charge is accepted or denied.
Plot hole: When Jack and The Duke are told to leave the plane they are still in New York, they then get train tickets from Grand Central Station, also in New York. Yet somehow the plane they left from is already in Los Angeles before the train leaves the station. How did the plane get from New York to Los Angeles that quickly?
Continuity mistake: When the Duke falls into the water he has a pair of handcuffs only on his right wrist. When he is shown flowing downstream he has the cuffs only on his left wrist. The next shot where his hands can be seen the cuffs are on the right wrist again.
Continuity mistake: When Jack and Jonathan got off the bus, Jack holds in his hands a brown folder or dossier (I guess the script) when they were about to be arrested against the bus. The second after there is no such folder.
Continuity mistake: When Jack Walsh is in the diner after losing the Duke to Marvyn he can't light his cigarette with his lighter the man behind the counter gives him a pack of matches and say "keep them", but when Jack brings the Duke to LA airport he comes down the escalator and lights up a cigarette with his own lighter.
Continuity mistake: Jerry Geisler is at his desk just about to light a cigarette when Jack Walsh calls on the phone. Geisler angrily slams down his cigarette and lighter to answer the phone. In the time it takes him to say "Eddie, it's Jack" he has picked up both the lighter and cigarette and lit the cigarette.