h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

One thing I found interesting when I learned of it was that some of the costume pieces from the Planet of the Apes movies/series later found use in Star Trek: the next generation. In the episode where Worf goes through his "rite of ascention" ceremony they didn't have enough Klingon boots to go round so the studio used boots that the actors playing gorilla's in the movies had used to make up the difference. I believe John Tesh of Entertainment Tonight was one of the holographic Klingons in that episode.

Also during the filming of the movies the actors unconsciously grouped themselves during lunch periods. Gorilla's with other gorilla's, chimps with other chimps, and orangatangs with other orangatangs. The filmmakers also included a joke in the 'trial' scene in the first movie. One orangatang covers his eyes, another his ears and the third his mouth, thus forming the hear, see and speak no evil group of primates. lol.