Although Richard Burton and Stanley Baker had been close friends since they were teenagers, this was the only time they acted together in a movie. Burton later recorded the narration for Baker's film Zulu (1964).
Robert Rossen was lobbied by photojournalist (and later co-producer of Cassavetes) Sam Shaw to consider John Cassavetes, then a struggling young actor in New York, for the title role in the film. Rossen rejected Cassavetes for the role, but the blacklisted director and the young actor became close friends over the course of the next few years. They shared many opinions about dramatic construction, acting and directing, and Rossen would give Cassavetes a lot of help a few years later on Shadows, Cassavetes' first film as a director.