Continuity mistake: When Frosty gets off the train because Karen gets sick, from the magician's view it appears the train is slowing down and is very close to Frosty, but when the shot goes back to the magician, the train appears to be going much faster and is much further away.
Continuity mistake: When Charlie Brown is doing the dog food for Snoopy, the amount of food in Snoopy's dish changes between the kitchen and the dog house.