I was thinking of the sequel to the original film. Heston played a supporting role in the second film.
You wrote episode so that reads as tv series.
The tv series is a sequel. Heston certainly was in second movie.
I think the tv series is meant to be another ten years more into the future and this second lot of astronauts do find out Heston's character had been down similar path to them well before them.
"The series begins with the crash of an Earth spaceship that encountered a time warp while approaching Alpha Centauri on August 19, 1980. The spaceship is crewed by three astronauts, one of whom has died in the crash. The other two astronauts, Colonel Alan Virdon and Major Peter J. Burke, are unconscious but are rescued by a old man who carries them to an old bomb shelter. After the old man opens a book containing historical text and pictures of Earth circa 2500, the two astronauts are convinced that they are indeed on a future Earth."
"The crash is also witnessed by a young chimpanzee who tells his father, a village official who alerts the authorities. Ape councilor Zaius (an analog of the character from the original movie), notes that another such incident occurred ten years earlier. He orders the chief gorilla, Security Chief Urko, to find the humans and bring them back alive. Zaius wants to find out as much as he can about the humans before they are eventually killed. Zaius doesn't trust Urko to follow his orders and bring back any surviving humans, so he sends along his newly hired chimpanzee assistant, Galen.
Both Virdon and Burke go back to their ship to check the ship's chronometer. They are more than 1000 years in the future from when they left Earth. Virdon insists on retrieving the ship's flight log in the hopes that they will be able to analyze it and be able to return to their own time period, but while they are at the ship, they are captured, and the old man is subsequently killed by a group of apes."
Planet of the Apes (TV series) - Wikipedia
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