The special effects were so good that footage from this film was used in numerous other pictures produced well into the 1960s.

The #1 box-office attraction of 1940 (excluding the roll-over receipts for Gone with the Wind (1939)).

When the film was released in Britain, it was heavily edited due to their strict laws against animal cruelty.

In the remake One Million Years B.C. (1966), Robert Brown wore identical make-up when playing Akhoba to that worn by Lon Chaney Jr. in this film.

In order to get the lizards to move, heaters had to be turned on full blast because reptiles don't move in cold weather.

Originally, D.W. Griffith was supposed to direct the film. However, he quit in the middle of filming so Hal Roach and his son completed the project.

According to an article in "The New York Times" on 21 April 1940, D.W. Griffith, who worked as producer on the film, had his name removed from the credits because of a disagreement with Hal Roach. He said, "Mr. Roach did not feel that it was necessary to give the characters as much individuality as I thought was needed, and so I did not wish to appear responsible for the picture by having my name on it."

Victor Mature and Carole Landis starred together in the Film Noir 'I Wake Up Screaming' a few years later.

Lon Chaney Jr. designed his own makeup for Akhoba, but couldn't use it owing to Cosmetician's Union rules.

For its 1946 theatrical re-release, Favorite Films often paired this one with the re-release of Hal Roach's Of Mice and Men (1939).

The film has been colorized.

Final film of Rosemary Theby.

This film was first telecast in New York City Tuesday 24 August 1948 on WPIX (Channel 11), as part of their newly acquired series of three dozen 'Hal Roach (I)' (qv_ feature film productions, originally theatrically released between 1931 and 1943, and now being syndicated for television broadcast by Regal Television Pictures. Its earliest documented telecasts in St. Louis took place Wednesday 15 December 1948 on KSD (Channel 5), in Boston Sunday 17 July 1949 on WBZ (Channel 4), in Los Angeles Tuesday 30 August 1949 on KTLA (Channel 5), in Atlanta Wednesday 31 August 1949 on WSB (Channel 8), and in Cincinnati Sunday 6 November 1949 on WCPO (Channel 6).