Many of the screams heard are stock sound effects that can also be heard in many Republic movie serials.
That giant worm with the "octopus-like arms" seen in this film is a prop from the unused spider pit sequence from the original King Kong.
The sounds of the scorpions are the same sounds as the ant chirps in Them!.
The trapdoor spider that attacks Juanito in the scorpions' underground home is one of the original models left over from the famous deleted spider sequence in King Kong
The volcano shown at the beginning was Paricutin which erupted in 1943 and was active for about a decade.
While filming the stop-motion effects at Tepeac Studios, O'Brien and Peterson were assisted with miniature set construction by Ralph Hammeras, who was at the same studio filming the visual effects for The Giant Claw.
Willis O'Brien and Pete Peterson began filming the special effects of this film in a large remodeled dressing room at the Tepeac Studios in Mexico City, but when money became tight they finished the picture in Peterson's garage in Encino, California.