Continuity mistake: In the first film, it is mentioned several times that Kevin is 8 years old. However, in this film it is stated that he is 10. When his parents are in the Miami airport security office, they say that he was left alone last Christmas. That would make him 9. Both films take place the same days, from about three days before Christmas until Christmas morning, so even if Kevin is born around Christmas time this is still a mistake.
Continuity mistake: The tiger bites the seat off the suitor's trousers, allowing the viewer to see his polka-heart boxers. When we see the tiger in the courtyard, he has a part of the same boxer shorts in his mouth. So if he bit off the seat of the trousers, shouldn't he have purple cloth in his mouth? (00:11:45)
Continuity mistake: When Adam Banks is playing in one of the games, he scores a goal and his teammates on the bench stand up and cheer when he scores. Problem is, Adam Banks is on the bench too.
Continuity mistake: In the scene where Gabriel Byrne is dancing around the fire with the travellers, he is wearing a large leather coat. After the police come and go, he's no longer wearing the coat. In the same scene, it shifts from night to day quite quickly, too quickly to be a sunrise.
Continuity mistake: As Jack Kelly rides the horse near the end of the "Santa Fe" sequence, his hat is waving behind him. When it cuts to a different angle the hat is on his head. Note: This was a specific detail put in by the director, symbolizing the boy's mental transition from New York to Santa Fe. However, it failed and is commonly seen as an editing mistake.
Continuity mistake: When Rocky and Colt go to the bathroom to attack Hammer after he drank the laxative, Colt thrusts a plunger to Hammer's face. As Colt thrusts it backwards, Hammer's face gets pulled forward, sending his ponytail over his head. In the next shot his hair is neat and tidy, not over his head.
Continuity mistake: When Nick and his dad walk to the kitchen to see what happened with the baby, Nick leaves the newspaper sideways on the table. He and his dad run back screaming and hide behind the couch. Angle changes and the newspaper is now placed perfectly straight.
Continuity mistake: In some shots there is no steam coming from the steamboat.
Continuity mistake: In one shot when the robbers are driving the bread truck, a door appears on the driver's side.
Continuity mistake: As Hampton's family leaves town for Happy World Land, the car's odometer approaches 100,000 miles and, at this point, Wade grabs a camcorder with his right hand and starts videotaping the event. But in the next shot however he's steering the car with both hands - and still operating the camcorder somehow. (00:05:50)
Continuity mistake: When the song about Ebeneezer Scrooge is about to end, just as Ebeneezer is walking down the last lane, the first Muppet you'll see to the left when he has come down the stairs is wearing a red weird hat. Just a second after Scrooge has walked past the lady with the funny hat, when they sing, "If being mean's a way of life you practice and rehearse," you see the same Muppet with the same hat, now standing in front of Scrooge. She had no time to get there between the two shots.