Errors in geography: When Bolt is in New York City, we can see a pedestrian "WALK/DON'T WALK" sign. In New York City, those signs show a white walking character (walk) and a red hand (don't walk).
Revealing mistakes: Near the beginning of the film, Calico is sitting with a cat on his right shoulder. Their reflection is shown in the glasses of a man directly opposite. The reflection shows Calico and the cat in the same position instead of being reversed, as a reflection would be.
Factual errors: The roll-up door on a U-Haul truck cannot be unlatched from the inside.