Continuity mistake: During the scene when the Polar Express slides across the ice and the conductor is telling the train controllers to head for the tracks, the distance between the train and the tracks keeps changing.
Continuity mistake: When the boy runs out of his house, as the train is arriving, they make a point of showing his footprints in the snow along with his sliding leaving long marks. However, when they pan back it is his footprints that are gone.
Continuity mistake: After the Hot Chocolate scene, the little girl takes a cup to the boy in the last car. When she leaves her seat, there is no ticket there, but the boy sees that she left it behind.
Continuity mistake: Nearing the end of the scene where the boy and hobo are jumping from the roof of one passenger car to the next on skis, the camera shot changes from a close-up to a distant view. In this distant view you can plainly see that they have just two more passenger cars to jump onto before hitting the coal hopper. However, when the camera returns back to a close-up shot, they jump three passenger cars before the boy hits the coal hopper.
Continuity mistake: During the hot chocolate scene, the girl places a cup of hot chocolate under her seat. She is given another hot chocolate and puts that one under the seat too, but the original one has vanished.
Suggested correction: The first time the girl puts the cup of hot chocolate next to her on the seat, then later puts it under her seat.
Suggested correction: She puts it beside her then next to the seat.
Continuity mistake: After the kids reach the North Pole and they line up outside of the train, Hero Boy and Girl are at the back of the line and we can see the other kids in front of them. In the next few shots, they discuss helping the Lonely Boy. When the camera comes back to the same point of view of the boy and girl being in line, the rest of the kids have disappeared behind them.