Factual error: Just after Littlefoot and the others get stuck in the tar, we see Cera being chased by a group of Pachycephalosaurus. They act like they want to eat Cera, which is the error because the Pachycephalosaurus was an herbivore, not a carnivore.

Audio problem: Littlefoot's lips don't move when he says "Cera, you came back." while pushing the boulder on the Sharptooth.