 When this film was released in the US in 1970, it was released on a  double bill with War of the Gargantuas. "War of the Gargantuas"  was a sequel to Frankenstein Conquers the World which stared Nick  Addams. Nick Addams was signed to be War of the Gargantuas  however, because of his untimely passing, Russ Tamblyn was cast in  his place.