The original title of the film was "Duel in the Wind." Lee Van Cleef came up with the Italian title while discussing the movie with John Phillip Law who sighted the film was a "man to man" story. Van Cleef remarked, "Why don't they call it 'From Man to Man'?" The Italian producers liked how it sounded in Italian ("Da Uomo a Uomo") so much they used it. And then the film was subsequently retitled "Death Rides a Horse" in English speaking markets, which Law said he never liked.
When we first see Bill Meceita (John Phillip Law), he is practicing his shooting. The first revolver he shoots, a six-shot Colt Peacemaker, turns out to be a 9 shooter, and the second is an 11 shooter.
During the card game between Cavanaugh & Meceita, Cavanaugh shows his hand "4 aces" with the cards being in As, Ah, Ac, Ad, Js order. Right before the third strike on the piano a quick shot shows the cards are now in an Js, Ah, Ac, Ad, As order.
When the bad guys charge the village after the fire is gone, there are lot more than there were before. Also, the same people fall off their horses in identical scenes right after each other.
Station master: This guy told me a pal of his should be coming along. He said I should give you the horse, and a kiss. The horse is there, waiting for you. Ehh, now now, where do you want that kiss?