When the Neanderthal is scared by the woman wearing a face mask and jumps into a bush, he is wearing big white shorts under his loin cloth.
When the musicians are playing the steel pan drums, a guy wearing an orange shirt at the bar moves to the beat as the waitress serves Bart and Betty at the table. The scene immediately cuts to another angle at the table and the guy at the bar has stopped (it was just another angle of the same scene, not another action.)
When Bart chases after Julio in the storm, it alternates between a clear day and night time. It is not a "day for night" shot, it was obviously shot on a sunny day.
When the caveman is found on the beach by Hacker, he is frozen solid. Yet less
than an hour or two later he is fully thawed and alive. It would take
at least a day to thaw completely even in the tropical climate.
The two Marx dinosaur toys that Julio says he got from sending in box-tops were never giveaways with any product. They were only sold in stores, a part of a set of Dinosaur toys by Marx.
Obvious stunt double as Julio runs away from
cantina. Actor Alan Roberts is much shorter
and smaller in stature.
When the caveman hears the ham radio screech
and starts to swing his ax at it, there is no drill
on the table left of the radio. When the ax actually
hits the radio, the drill magically appears.
When the boy and caveman meet in the kitchen, the oven changes to a refrigerator when the boy looks for food.
The caveman has only been alive just over 2 hours
or so. Where did he find time to hunt, kill, and skin a rabbit for Betty
to cook for him in the cave?
Mike Hacker (apparently a Spanish-speaker from his accent) calls Chica his "little tamale". The correct Spanish singular is "tamal"; "tamale" is an incorrect Anglophone singular made from the plural "tamales".