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.
Factual error: When Mrs. Krank tries to snatch the Christmas ham in the parking lot of the grocery store, you can see trees with green foliage in the distance. Chicago never has green foliage on trees in the month of December.