During special effects work on the film, the stop-motion animation crew used their brontosaurus model and miniature jungle set to film a shot for The Odyssey of Flight 33 (1961).
Marcel Delgado was given less than half the time originally agreed upon to create the dinosaur models used in the film. The studio initially agreed to give him five to six weeks, as he requested, but two weeks later he was told that they would begin production on Tuesday.
The roar of the Tyrannosaurus would be re-used many times in later movies and TV shows.
Originally, it was intended for Steve McQueen to star in this film, after he had appeared in The Blob (1958) from the same producer and director. However, McQueen had been so difficult to work with, that they didn't even bother.