Among those who saw '40,000 Horsemen' on its US release was a young Clint Eastwood. Richard Schickel writes in his 1996 biography of Eastwood: 'Treasured among these films and stars that Clint Eastwood saw while growing up is one slightly more exotic title, Forty Thousand Horsemen. The story of an Australian cavalry brigade that fought in Palestine in World War I, it starred Chips Rafferty, was made in 1940 and entered the world market a couple of years later. Its dialogue contained a few mild, but in those days shocking, cuss words. Clint remembers going to it with his family and, when the first "hell" or "damn" was heard, being aware of respectable citizens leaving the theater. The Eastwoods soon followed, but "I snuck back later, because I wanted to see the whole movie; it had a lot of action - horses, and lancers and what have you."'
Director Charles Chauvel's Uncle, General Sir Harry Chauvel, had commanded the New Zealand and Australian desert corps in Palestine in the First World War. However Charles never mentions his uncle's part in the battles, because he didn't want the film to be seen as a family tribute.