Revealing mistake: When the Pterodactyl is flying around with the egg, its shadow isn't cast as she flies over the trees.
Factual error: The average Iguanodon is estimated to have weighed around 3.4 tons, while Carnotaurus probably weighed about 1.5 tons. By this logic, during the final Carnotaurus encounter, the rocks at the edge of the cliff should have crumbled when Kron tried to escape, but remained intact until the Carnotaur was at the edge of the cliff. This is because the Carnotaurs in the film are inaccurately depicted as being T-Rex - sized animals.
Continuity mistake: When Aladar is trying to help Eema get up, his eyes turn blue in one shot and in the next, they turn back to the usual green. The same thing happens at the end of the movie, when Aladar's baby hatches out of the egg.
Continuity mistake: When Aladar arrives at the nesting grounds and sees that the herd isn't going to make it over the wall he turns back to find them and lead them to a better path. On his way to the herd he runs into a Carnotaurus and in this scene it's suddenly nighttime as opposed to the scenes before and after where it's broad daylight.