DeForest Kelley rather famously told an anecdote about the filming of this movie in his later years on the Star Trek convention circuit, about the time Princess Sofia of Greece was visiting the set and Kelley flubbed a scene by falling over a chair onto his backside and saying "Oh, shit," in front of the princess. Henry Fonda told him the following Monday not to worry about it because he had danced with the princess over the weekend and ascertained that she had no idea what "shit" meant. This did not stop Kelley from getting a standing ovation at the commissary when the cast and crew broke for lunch.
Henry Fonda's name in the original US version is definitely "Clay," but some other sources refer to him as "Curt." Perhaps some foreign versions of the film renamed him because "Clay" as a first name was unfamiliar there, while "Curt" was.
Film debut of Gary Lockwood.
Two important roles were played by actors going very much against type. The often strong, tough, macho Anthony Quinn here is cast as a hesitant, even weak man. Tom Drake, who once played sensitive composer Richard Rodgers and while at MGM specialized in nice, clean-cut "boy next door" roles, here is cast as the chief villain, the evil boss of the vicious "San Pablo" gang.