Carrie, the chimp that plays Voodoo, is a full grown adult chimpanzee. Adult chimps are rare in film due to their strength and aggression.
The script originally called for Link to be a chimpanzee. When Locke got the role, Link was changed to an orangutan, although trainer Ray Berwick dyed his fur black and gave him prosthetic ears, to make him look more like a chimp.
Locke, the orangutan who plays Link, and Jed, the chimp who plays Imp, go in wheel chairs before they start filming to save their energy.
Director Richard Franklin was asked to use make up for the apes but he elected to use real apes, and editing techniques to make it seem how they were reacting. "From a technical viewpoint, it was really not as hard to do as I had anticipated," said Franklin. "But there was a lot of pressure on me, even at the last minute, to use men in suits, which I thought would be dishonest. We weren't making a fantasy, and we weren't making Greystoke with its fable-like qualities. We were doing something which was supposed to be based on what chimps can really do. "