The armored creature that attacks McBride and his group in the cave near the end of the film was actually a model of the Late Permian reptile called Scutosaurus.
This was the final film from the British production company, Amicus.
Paintings by Frank Frazetta appear in the film either as murals on walls or as the inspiration for tableaux performed by the characters.
The seaplane bears the "Hat in the ring" insignia of the 94th Aero squadron from World War I. It was the first American unit to arrive in France during the war.
During an interview in 2020, actress Dana Gillespie (Ajor) talked about how many fans feel her skimpy outfit and robust physique were highlights of the film. She joked, "Well, it's mainly because they always seemed to give me the chamois-leather bits that Raquel Welch had discarded from One Million Years B.C. (1966). My costumes were actually much bigger than hers, she's got the right shape for a bikini which I clearly haven't, really. But if you play a native girl, there's only one sort of costume you can be put into: it's either bits of fur or bits of suede leather."