Approval of God: Pierre Boulle had thought his novel unfilmable and was surprised at how well the movie version worked. He even wrote a treatment for a sequel to the film ("Planet of the Men"), that while discarded for Beneath the Planet of the Apes ended providing some inspiration for Conquest of the Planet of the Apes.
The iconic line begins as "Take your stinking paws off me...", not "Get your stinking paws off me..."
The wham line is "God damn you all to hell!" "God" is often omitted when quoted.
Cast the Runner-Up: Linda Harrison played Zira in early makeup test footage opposite James Brolin, but was later cast as the human Nova. She got both roles because she was dating the studio head at the time, but her former beauty pageant looks helped with the latter.
Creator Backlash: Pierre Boulle hated the ending with the Statue of Liberty, thinking humanity's end should have been more tragic rather than self-inflicted.
Enforced Method Acting: Charlton Heston's voice during his famous "take your stinking paws off me" line was made more realistic by the fact Heston was quite ill during the filming of the scene.
Franchise Zombie: The sequels and TV shows. Both the second and third movie were intended to be the last in the series (5 were made).
Magnum Opus Dissonance: Fox only greenlit the movie because they felt Arthur P. Jacobs could do it on a low budget compared to the Troubled Production that was Doctor Dolittle, the movie they were hoping to turn into a Cash-Cow Franchise. Dolittle bombed; Apes became a seminal sci-fi film that started a profitable series.
The Other Marty: Dr. Zaius was originally going to be played by Edward G. Robinson, who got as far as filming the early test footage, but his ill health did not mix well with the heavy makeup, and he quit. The surviving footage shows Robinson playing Zaius as a cynical Deadpan Snarker, in contrast to Maurice Evans and his interpretation of Zaius as a bombastic authoritarian.
Orangutans, chimpanzees, and gorillas were though to be single species when the movie was made. Now there are three recognized orangutan species, two chimpanzees, and two gorillas, which makes the idea of they all coming together to make a single civilization even less plausible.
Taylor's final rant at the end was thought up and written down by Charlton Heston on the day of shooting that scene. It adds much more power to that Wham Shot, even after repeat viewings.
The shot of the three judges at Taylor's hearing doing the Monkey Morality Pose ("See No Evil, Hear No Evil, Speak No Evil") wasn't meant to be in the movie, it was just the three actors goofing around between takes and they decided to put it in the film.
Ursula Andress was the first one considered for the role of Nova, and among those who tested was Angelique Pettyjohn, best known for a Star Trek episode where she plays a green-haired warrior.
The early scripts for the movie had a closer resemblance to Pierre Boulle's novel, but budget constraints forced the change to the primitive ape society of the film.
Jonathan Harris was offered the role of Dr. Maximus, but turned it down due to the make-up requirements.
Scenes were scripted and filmed revealing, near the end, that Nova was pregnant with Taylor's child. The scenes were cut out of the final print, as it was felt that they changed the focus of the ending, leaving the door open to a sequel Heston didn't want (but got anyway).
In the early scripts and the test footage, Taylor's name is John Thomas.
Segregation appeared spontaneously behind the scenes during filming: the chimpanzee actors ate with other chimps, gorillas with gorillas, and orangutans with orangutans. They were never told to do this.
Once, some of the gorilla actors rode from the makeup area to the set in a convertible with the top down, wearing their full gorilla makeup, wigging out some observers on the way.
The Statue of Liberty scene was based on a scene from an earlier sci-fi story.
Contrary to widespread belief, Stewart wasn't played by Natalie Trundy (who did appear in all the sequels), but rather by Diane Stanley.
at the time, but her former beauty pageant looks helped with the latter.