Some of the cave men have "farmers' tans."
Near the beginning of the movie, the Symbol Maker (Leslie Bradley) asks; "Where's the boy? Beyond the river?" His left sleeve strap of the Symbol Maker's fur outfit is sewn together. The next scene the strap came undone and he is holding the strap under his left arm. Next scene the strap is now tied together with a leather shoelace. Later in the movie this strap is shown tied together in two different spots. Apparently they were having problems keeping this sleeve strap together throughout the movie as it changes constantly.
In the opening scenes the cave people talk with grunts and unintelligible sounds. But then the Symbol Maker comes into scene and speaks perfect English. Throughout the rest of the movie everyone speaks perfect English.
The title has a word spelled wrong. "Cave Man" should be spelled with out the space between words. It should be "Caveman".
Although they are supposed to be "cave men," the men have combed hair and are cleanly shaven.
Cavemen who say 'aye' like a sailor.
The hero wears a combat knife on his right hip. Steel won't be invented for another 10,000 years.