Revealing mistake: You can see Hero Boy putting the ticket in his pocket after getting it punched the second time, before finding his seat on the return journey. However, the ticket slowly evaporates in the air as he is about to put it into the pocket. His hand thus enters the pocket ticket-less.
The Polar Express (2004)
1 revealing mistake
Directed by: Robert Zemeckis
Starring: Tom Hanks, Michael Jeter, Chris Coppola, Leslie Zemeckis
Factual error: When hero boy and girl and Billy are on the runaway car at the north pole, they crash into the stopper at the end of the tracks. They are flung backwards when in reality, due to inertia, they should have been flung forward into the guard rail.
Hero Boy: At one time most of my friends could hear the bell, but as years passed it fell silent for all of them. Even Sarah found one Christmas that she could no longer hear its sweet sound. And though I've grown old, the bell still rings for me, as it does for all who truly believe.
Trivia: The ticket that gets lost often times floats almost exactly like the feather does in the beginning of "Forrest Gump" (1994), another Robert Zemeckis-Tom Hanks film.
Question: How would the train have been able to go back the same way with the ice on the lake cracking?
Answer: Because it's a magic train.