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Character error
General Urko refers to a gorilla soldier as "one of his best men". Apes in this universe would never use the term "man" or "men" when referring to another ape. It would be sacrilegious.
When Jeff is testing the recently recovered laser, he's shirtless. Then it cuts to a wide shot, and he's wearing his red sweater. Then in a close up he has bare shoulders again.
Near the end, when Dr. Zaius announces that "There has been no invasion of the Planet of the Apes", the side of General Urko's helmet has not been painted, and the background plate is visible through it.
General Urko refers to a gorilla soldier as "one of his best men". Apes in this universe would never use the term "man" or "men" when referring to another ape. It would be sacrilegious.