This is the only movie in which Humphrey Bogart and Spencer Tracy co-star. Although Tracy and Bogart were good friends, they never appeared in another movie together, as Bogart was tied to a contract with Warner Bros. for much of his career while Tracy was bound first to Fox, and then (most famously) to MGM. When the freelance era rolled around in the 1950s and both were free of their studio contracts, the two talked about co-starring together in a picture, but according to Tracy's lover Katharine Hepburn, they could never agree on who would get top billing (although Tracy was the more respected thespian, Bogart was more popular at the box office; however, after playing second-fiddle to Clark Gable for many years at MGM, Tracy wasn't about to accept second billing at that time in his career). Hepburn recalled they considered a suggested compromise that would have created an "X"-shaped credit in which Humphrey Tracy would have co-starred with Spencer Bogart, when read normally.
This is the first John Ford film in which Spencer Tracy appeared: their second collaboration took place three decades later, when Tracy starred in Ford's The Last Hurrah (1958). It is strange to realize that these two great Irish American icons only collaborated two times (Tracy narrated How the West Was Won (1962), one of the sequences of which was shot by Ford, but that doesn't count as a true collaboration), but for most of their careers, they were bound to different studios, Ford to 20th Century-Fox and Tracy to M.G.M. By the time the freelance era rolled around in the late 1950s, Tracy was appearing in very few movies.