Continuity mistake: When Rabbit and his mom's boyfriend were kicking each other's ass inside the Smith's trailer, Rabbit pushes or punches the boyfriend from the kitchen to the living room, breaking a small wooden post in a quick shot. A few shots later, when Rabbit returns to the trailer, the wooden post is intact. There was no time to fix it.
Continuity mistake: When Shawn is teaching the new drummers not to look at their drums while they play, he and Devon play together until Shawn drops a stick. At this point, Dr. Lee comes over and starts playing with Devon, until Devon drops a stick. The drum stick falls from Devon's hand and bounces around on the field. In the next shot, Dr. Lee is talking to Devon, neither has moved, but now Devon has both sticks in his hand.
Factual error: An old man appears with children following him. This is supposed to be pedagogue Janusz Korczak. It appeared as if he was just wearing a suit and a Jewish arm band. In the Warsaw Ghetto, Mr. Korczak never wore an arm band and wore his WWI Polish Army Uniform, both as acts of defiance. He was beaten and almost put to death (he had connections) for not wearing an arm band so having one on in the movie is inaccurate.
Factual error: After Berry and one of the Country Bears get in the bus to find the others, they show a scene with the bus going along a road and Berry leans out the window. Here you can see the side of the bus is spick 'n' span clean. Then, later, the bus is as dirty as it was when it left the shack, very noticeable at the start of the carwash scene.