Robert Ryan did his brief cameo for free. He was holidaying in Florence and did his three scenes in Madrid as a favor to producer Philip Yordan. After a considerable absence from the screen, Yordan had paid Ryan $150,000 for his role in Battle of the Bulge (1965) and Ryan was extremely grateful.
According to Swedish press at the time of the films TV premiere, the flume ride sequence was filmed in Sweden rather than - as originally considered - Canada. A trip across the Atlantic was too expensive.
Robert Shaw earned $350,000 for his portrayal of Custer, whilst his wife Mary Ure received only $50,000 for her turn as Custer's wife.
The film was criticized as gloomy and historically inaccurate. Robert Shaw was felt to be at odds with both his accent and his character. Custer was of German descent, yet Shaw appears to be using an Irish accent in the film.