9. Olympia DOES Exist
About halfway through the film, we learn the shocking twist that Olympia, the apparent home world of The Eternals, where they are sent out to nurture growing worlds and civilizations into maturity, was in fact all a fabrication by the Celestials. An ever enticing carrot on an infinitely growing stick, meant to keep their little tin soldiers nice and obedient.
However in the comics, that was not the case. Olympia does, or at least DID (it varies from moment to moment) exist, and The Eternals actually are from there.
The main similarity with the movie is that the Celestials still created The Eternals. They just also made Olympia, I guess as a way of keeping them all in one place. Gotta keep track of your Jack Kirby alien god allegories, after all, they can make a real mess if left to their own devices.