Revealing mistake: In the last third of the film just after the announcement that Kong is coming, a native jumps out of his hut, loses his balance and falls by a chicken coop. His wig comes off and gets caught on the fence.
Factual error: There are just a couple of things wrong about the gas grenades used in the movie: gas grenades do not explode, they spray their contents; and second: if the gas really is that powerful, it should be used with more caution; a simple sudden downwind breeze into an uncontrollable gas cloud, and the users would become their own victims.
Continuity mistake: Just before Kong is gassed and captured, he picks up someone and bites his head. In a close up, he has them by the legs, then in the long shot he is biting their head. (01:14:30)
Factual error: A creature of Kong's size would not be taken out that easily with the gas grenade as in the movie, for: 1) it explodes far too low for the gas to affect him; 2) even if the gas had reached his breathing organs, it would have taken more and prolonged exposure to knock him out.
Visible crew/equipment: As the villagers are running away, look to the back right of the screen. There is a camera crew member standing and watching. (01:21:40)
Revealing mistake: When the men are running away from the Brontosaurus, it is quite obviously sped up. (00:56:40)