Factual error: The group finds an underground sea and there is a flock of pterosaurs flying overhead. The professor identifies the pterosaurs as the missing link between pterodactyls and archaeopteryx. This is not true as archaeopteryx (and other birds) did not descend from pterosaurs but from a branch of theropod dinosaurs.
Continuity mistake: The professor knocks a hole in the side of a tunnel and hot water and steam gush out. The group is then distracted by a boulder traveling through the tunnel. After the boulder passes, there is no longer any steam or water gushing from the hole in the wall.
