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.
Revealing mistake: The Bears' bus is driving by a green highway sign reading something like "Nutville 2". Road signs are normally made of something rigid. But as the bus passes, the sign ripples in the breeze, and you can tell it's just made of fabric or plastic.