Corrected entry: If these tracks are in plain sight why would any of these kids doubt Santa? They could follow the tracks and go to the north pole.
Corrected entry: As the train goes up the corkscrew the cars bend like rubber to match the tighter top curves. (00:41:30)
Correction: Not a mistake. The Polar Express is a "magic train" as the Hero Girl pointed out earlier in the film, and can do incredible things that other trains cannot.
Corrected entry: When the hero boy opens the window to grab the girl's ticket, you see few cars between them and the engine. When the shot pans out as the ticket flies away, there are several more cars than before.
Correction: The Polar Express is a magic Christmas train that defies logic and physics throughout the movie. Further, this whole experience could be a dream of the Hero Boy, so it is likely the train would change the number of cars, as well as bend with the tracks as it corkscrews up a mountain, etc.
Corrected entry: At the end of the movie when they drop off the kid. As the train slows you see steam coming from each of the cars. Steam should only be coming from the main locomotive, where the boiler is, so there's no reason why steam is coming from each car unless its powered but it's not.
Correction: Railroad cars in the days of steam locomotives had what is called "steam heated systems" where a series of pipes would use the heat from the locomotive's firebox to warm the coaches. There would be an exhaust valve on each car to control the heat of the car and let excess steam out. Steam would also appear on the valve that is left open on the end of the train (normally where the next valve would begin if there was another car).
Passenger engines have a system to send steam from the boiler back to heat the cars. Only passenger engines were so equipped. I find it hard to believe they would leave the steam line open at end of train as this would seriously lower the steam pressure for the whole consist. The steam was the power to move the train as well as heat it in cold weather.
Corrected entry: 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.
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.
Stupidity: The Engineer and Fireman of the Polar Express train crew should have known better than to not bend back the the metallic prongs of the cotter pin, which would have prevented the cotter pin from coming loose and causing all those problems in the driving of the train.
Suggested correction: As you yourself stated, the whole thing is likely a dream, where "normal" reality doesn't apply. In the "real world", the train would never be able to do any of the things that it does in the film.
Dream or not, it is still a stupidity of the train crew to not secure a pin that could work itself free of the controls of the locomotive.
Dreams are often unrealistic. There is no mistake.
The entry doesn't say anything about the entire trip to the North Pole being a dream.
Continuity mistake: Throughout the movie, the number of cars the train has changes. The scene where Hero Girl's ticket is surrounded by a pack of wolves shows the train having around 20 cars, but the scene where the train's on the ice shows it having 5.
Suggested correction: The entire journey is likely just a dream. There are many things in the movie that cannot happen in the "real" world, and the number of cars changing is just another aspect of the dreamlike nature of the trip.
Correction: The whole thing is most likely a dream, so the train tracks would not be visible to the kids in their daily lives. Also, what kid in their right mind would walk to the North Pole when they could dream up a magical train to take them there and also get served hot chocolate by gravity-defying dancing waiters?
Scott215