Blooper

The professor thinks the tablet sealing the cave was made by "cavemen, possibly even [pre-human hominids.]" He'd be a lot more excited if he really believed this, as the first hominids in North America, Asiatic nomads, arrived after all pre-modern humans were already extinct.

The professor refers to the pottery as "incredibly primitive," and thinks it may be "hundreds of thousands of years old." The pottery shown is quite advanced, relatively speaking. In any event the oldest known pottery vessels data back only about 20,000 years.

The eoliths the expedition finds are now believed by scientists to be naturally formed objects. However, when the movie was made, they were believed to be the earliest known stone tools (hence "eolith," or "Dawn Stone.")