Many of the unlockable pictures in the galleries, as well as a couple of the dioramas, show scenes and enemies not actually included in the game.
There were going to be dinosaurs in the game. Live ones, not walking fossils like in the cliffs. Some unused concept art from Danny Richardson shows an enormous brachiosaur character, and art of the temple stage shows pterosaurs soaring in the background. A second jungle stage, named "Jungle 2", was also planned but ultimately dropped.