That iconic line, snarled by Charlton Heston at the top of his lungs, came from a script co-written by Rod Serling himself. Yes, the man behind The Twilight Zone wrote the original draft. Each ape mask was made by hand, and during lunch breaks on set, the actors couldn't sit at the same tables as their species. Heston later said the gorilla actors and the chimpanzee actors really did keep apart. The ending, with that Statue of Liberty reveal, was kept secret from nearly everyone, including the studio executives who paid for the picture.