Russell Johnson broke his toe while splashing around in the water during one scene. Due to the low budget of the film, director Roger Corman had a stage tech tape up Johnson's toe and immediately ordered him back in the water to finish the scene.
Paul Blaisdell was a member of Roger Corman's unofficial "stock company". He would normally build the monsters and special props for Corman's features. He turned this project down because he felt he could not do an adequate job for the money that was being offered.