The prototype version of the game contains several (very buggy) removed levels, but also some other changes. Most notably, Ripper Roo was originally located at the end of the first island, along with "Up The Creek". (This would explain his rather awkward placing in the final game, just two levels into the second island.) The fight is also somewhat harder, and his laugh is slightly lower-pitched. There were also "POW!" crates, which don't kill you (oddly enough), but make a pretty explosion when broken. A precursor to Nitro Crates, perhaps?
Tiny Tiger and the Komodo Brothers were also designed to put into this game (hence their cameo in the prototype intro above), however they were omitted and spared for Crash Bandicoot 2: Cortex Strikes Back.
Aku Aku was a sprite in very early stages of development and Crash collected actual fruit instead of the fictional Wumpa fruit.
As seen in an E3 build, "Whole Hog" originally became much more complex towards the end of the stage, with tribesmen hiding behind walls and boomerangs spinning through the air being thrown into the mix of obstacles to avoid. They were cut from the final game and replaced with more of the same obstacles used throughout the rest of the stage.