Some of the gaps between Conquest and Battle were filled in by a 2005 six issue comic called Revolution on the Planet of the Apes. It also contains some short stories, several of which fill in more of Caesar's background and several set in the gap between Battle and the original film, obviously trying to bolster the circular timeline theory.
Battle similarly had some stuff edited out, that, when put back, blatantly bolsters the circular timeline. There are scenes of the start of the mutant society from Beneath and a bit more involving the bomb.
Killed by Request: Charlton Heston (Taylor) didn't hatePlanet of the Apes (1968) or his character, but he wasn't interested in doing a sequel. He only participated in Beneath the Planet of the Apes as a personal favor, but he demanded that they kill him off in the first reel. As a compromise, he disappears at the end of the first reel and reappears at the end, to die in the last reel.
Note that the French term 'singe' from the original title includes both apes and monkeys, so this is technically a valid literal translation; however, gorillas, chimps and orangutans are all apes, not monkeys.
Inspiration for the Work: Pierre Boulle was inspired by a trip to the zoo where the apes' mimicry of human mannerisms set him thinking about the relationship between the two species.
Pop-Culture Urban Legends: Contrary to popular belief, Pierre Boulle didn't wish to use the same ending as the film.
Science Marches On: When discussing the different species of apes and their niche in the ape civilization, Zira, a chimpanzee, frowns with disgust at the gorillas, calling them meat-eaters. Ironically, since the book was written, chimpanzees have been observed to eat meat in the wild, whereas gorillas are almost completely vegetarians.
Regarding the TV series
Creator Backlash: Ron Harper felt the other1970s TV series where he played a human trapped in a strange world not of his own time and looking for a way to get home had better writing.
Edited for Syndication: Some of the hour long episodes were edited together for local TV reruns as two hour 'movies'.
Missing Episode: "The Liberator" didn't air in the United States during the original run. This is due to the controversy of its plot, which culminates in a man stockpiling chemical weapons (crude poison gas bombs) in hopes of using them to wipe out the apes who oppress his village.
Outlived Its Creator: Producer Arthur P. Jacobs died while preparing the series.
"Escape from Tomorrow" reuses the plywood spaceship model previously featured in the first three films. It also reuses the astronaut costumes from the first film.
Screwed by the Network: The series was cancelled partway through the creation of its fourteenth episode "Up Above the World So High", meaning only the first thirteen were ever aired.
