Both Star Trek and Planet Of The Apes were each hugely popular for more than a decade, entertaining on two levels, with both adventure and intelligent social commentary.
Here's a behind-the-scenes of making Planet of he Apes, that offers a number of long-unknown details, a number of them mind-blowing. Ties to a CIA exfiltration operation in Iran in 1979. Apes movie actors in costume unconsciously segregated themselves during filming into separate racial groups? That Pierre Boulle's original novel was purchased by producer Arthur P. Jacobs in 1963, before the novel was even released, and then no studio would buy it for many years. Charleton Heston was not the first actor chosen for the role. And apparently maybe not even the 2nd, 3rd or 4th. Multiple aspects of the movie were vastly changed, including the final scene with the Statue of Liberty. And that Charleton Heston actually wrote the most famous final line, that wasn't even in the script. Among many other aspects.
As I've partly detailed with Star Trek as well, it likewise went through many changes, and many elements we think of as essential to Star Trek, were in fact last minute additions. Such as James Doohan playing Scotty, who was initially not invited back after the series pilot, but a good agent negotiated to make Doohan/Scotty a regular on the show. The Vulcan nerve pinch. Spock having green blood. Things we see as written in stone and essential, were throwaway ideas that randomly made it on a whim into the final cut.
Hilarious that many elements in the original screenplay that were rejected and not used, were later used in the 2001 re-make... and audiences hated it.
