When the giant armadillo knocks over a tree, then turns toward the camera, his horn briefly gets caught in the tree roots. The horn bends, then snaps back, revealing that it is hollow rubber.
The cave people speak in a made-up language, but Lon Chaney Jr. slips after he throws Victor Mature out of the cave. His wife rushes forward, and Lon clearly says "Get back! Get down! Get back!"
Many of the depicted animals did not live in the same time or place, and some are just made up. However, the story is presented as a tall tale which the old professor spins for his gullible audience.
In some of the later scenes Loana's modern bra strap can be seen.
The professor smokes a pipe in the cave he is studying. A competent field researcher would never do this, as the fumes and ashes from the pipe would contaminate the paintings and artifacts.