In the title credits of the German Version, Riccardo Freda is credited as "Richard Freda", making the Director's first name sounding more German as Freda wasn't very well known in West Germany.
Though not an adaption of original material by Edgar Wallace, this film was advertised in Germany as part of the famous Edgar Wallace Series. It was such a huge flop that the Producers at Rialto Film decided to delay any future plans to do further Edgar Wallace Films. Due to the great success of Dario Argento's "L'Uccello Dalle Piume Di Cristallo" (1969) which was advertised as an adaption of a story by Wallace's son Bryan Edgar, Rialto's series re-started in 1971.