When you first see the Albertosaurs, their teeth continually switch from black to white in between scenes.
The front legs of many animals have been pictured wrongly: while the predators did hold their arms in an anatomically correct way, the Troodon's arms weren't feathered enough: fossil finds suggest it had actual wings, with the feathers running down their middle finger, whereas the arms of the Troodon in this film were not more than mere arms with the feathers stopping at the wrist. The forelegs of the ankylosaur and the Pachyrhinosaurus, on the other hand, have been positioned wrong. Their toes should have faced outward, rather than forward, and the real animals had only three claws, not four.
The Albertosaurus is depicted as being a contemporary of Gorgosaurus. In actuality, this was not the case. Albertosaurus existed between 71 and 68 million years ago, and is a descendant of Gorgosaurus. Gorgosaurus was around between 76.6 and 71.1 million years ago, and was a contemporary of Daspletosaurus. Daspletosaurus was an ancestor of Tyrannosaurus which existed between 67 and 64 million years ago.
Whenever the Troodon turn their heads, their long feathers clip into their necks.
As the Edmontosaurus gather around to protect themselves, one of them is walking in air, as evidenced by its shadow.
When Patch catches the mammal through the snow, the tip of his tail clips into the ground for a moment.