Trivia

Most of the prehistoric animal reconstructions have been modeled after the artwork of renowned Czech painter Zdenek Burian. This is perhaps most apparent on the Brontosaurus, which is standing in almost the exact same pose as in Burian's famous piece and has the exact same detailing on its body. Strangely, the prominently-featured Stegosaurus and Ceratosaurus were not based on Burian's art, even though he has painted both animals, including the promotional paintings for this very film.

The US release version features newly-shot opening and closing sequences that were filmed at the Museum of Natural History in New York City. Four New York boys were cast because they vaguely resembled the Czech boys who starred in the original foreign version.

The serialized version of this movie was shown on television children shows. The most famous being Garfield Goose and Friends (1952) would often show this version during its run in five minute increments. This was the version that began with the boys in the USA.

At the end of the film when the boys are standing at the top of the cliff a bird can be seen flying briefly in the background despite the fact that the time period they are supposed to be in has no life.

A filmmaking class was assigned the task of recreating scenes from various Karel Zeman films using only the techniques available to him at that time. For this film, they recreated the mammoth sequence. To add to the recreation, they cast the original actors to be on the raft. The child actors were now senior citizens and one of the four had already passed away.