In an interview on the Anchor Bay DVD release Jesús Franco says he originally wanted Rosemary Dexter as Justine, but the American partners in the film insisted upon Romina Power. Franco compared her performance to a window dummy.
According to Jesús Franco, Romina Power was slapped for real by Mercedes McCambridge in the scene where the two of them are together and she has to hit her. "At each rehearsal: 'Pam! Pam!'... nothing! We couldn't save anything because she [Romina] would have had to react very strongly to being so brutally beaten. So Mercedes McCambridge asked me: "Should I try to hit her for real?". And I replied: "Of course! Go ahead". So we started shooting and she 'Pam!' She slapped her. It was just me at that moment behind the camera and I caught her reaction, which was the reaction of Romina Power being hit by an actress and not Justine, but we agreed that it was still excellent. Today people tell me: 'But she's good!'. She may be good, but then everyone should congratulate me and say thank you, because most of the time she didn't even know we were filming," Franco recalled.
Italian censorship visa #53569 delivered on January 4, 1969.