Eduard Roschmann was a real-life wanted war criminal living in South America. He became even more wanted after the book and movie, and he turned up dead, rumored to have been killed by O.D.E.S.S.A. to stop the search for him that the media had begun.
The character played by Hannes Messemer was not referred to by name in the dialogue. However, it is intended to be S.S. Gruppenführer Richard Glücks, former S.S. Inspector of Concentration Camps, who disappeared after World War II and is rumored to have been one of the founding members of O.D.E.S.S.A.
The supporting cast was mostly German. Most of the character actors and actresses were major movie and theatre personalities of the German stage and screen. The English-speaking players were given special coaching by dialogue director Osman Ragheb to acquire German accents which would be identical to those of the native actors and actresses. Not only did Jon Voight and Mary Tamm have to learn to use the accent, but had to do it with North German dialect nuances because of their characters' Hamburg origins in the story.
One scene took place in the well-known Salvator beer hall in Munich. Ex-soldiers were used as extras to take part in a rally of former S.S. men, with the beer running freely during the scenes to authenticate the enthusiasm.
The term "O.D.E.S.S.A." stands for "Organisation der ehemaligen S.S. Angehörigen", which translates to: Organization of former S.S. members.