The original German title, "Die Schlangengrube und das Pendal", translates to "The Snakepit and the Pendulum".
Decoration sets and paintings in the movie are done by Gabriel Pellon.
In the U.S., this was picked up by Hemisphere Pictures and released in 1969 in an edited and English dubbed version under the title "Blood Demon". It was used as part of a pre-packaged double feature with the Philippine horror film "Mad Doctor of Blood Island" (1968).
Partially shot in the german town Rothenburg ob der Tauber and at the famous Extern Stones in the Teutoburg Forest.
The wall paintings seen in the castle resemble "The Last Judgement" from "the Garden of Earthly Delights by Hieronymus Bosch.