Roger Corman (strictly a producer by then) was not afraid to follow trends. In fact, he insisted upon it. So Humanoids of the Deep contained copious gore and nudity and an entire plot built around monsters raping women, who then were ripped apart from the inside during, er, monster birth. (Wonder where they got that idea from?) So…date night!
They wanted the Gillman to do a cameo, but he was like, “Uh…no.”