Trivia

The movie is the end result of conflicting projects of director Jesús Franco and the producers. «I started doing a movie that was titled "Gente del rio", in which appeared Mengele who was hidden there, and was wonderfully played by Howard Vernon. "Gente del rio" was a film about some fishermen who live in a town in Central America and know that Mengele lives there, but nobody dares to come up to him. Until some of them attempt to catch him. The movie is their fight to get hold of that bastard. And they get him. It was based on persons I met in Brazil, former Nazis who lived like gods on some fucking rural estates, and what I wanted was to show the clash between these people and the humble people of the river. But the producer wanted to give more importance to the character of Mengele, but in Andrea Bianchi's shabby action movie way. I did not want to do that with that character, who is a sinister and sordid type, but who must be given another treatment, not as if he was a street whore. So I abandoned the film, and in the end I left it. I did not finish it, nor did I want to finish it, because it was wrong, and I did not want it to appear out there on video. Almost all the material that I did with the Italians is like this, they did me a thousand dirty tricks, everything went wrong, and that's why I have never admitted the film as mine. » - Interview of July 23, 2009, in "Jess Franco: de los márgenes al cine de autor. Análisis del relato cinematográfico", Tesis doctoral. Universidad Complutense de Madrid, 2009. (translated from Spanish and slightly edited)

Fernando Rey's cameo was shot in a single afternoon, at his own house.