Chuck Robeson (John Wayne's longtime stunt man) was meant to double for Jim Brown on some of the riskier stunts, with the director planning to put blackface on him. Burt Reynolds would not perform with him. Deeming it inproper and stated "Those days are gone, you better get a black stuntman here right now." When the production manager stated it was not in the budget, and "Fox would never go for it" Reynolds paid $500 out of his own pocket to pay for a black stuntman.
Whilst filming the fight on the cliff-top, Jim Brown mentioned to Burt Reynolds that he wasn't too keen on being so close to the edge of a serious drop. Reynolds replied, "If we fall, the newspapers will say 'Jim Brown and unknown actor die'".
Burt Reynolds plays a half-breed (half-white, half Yaqui Indian) native American in this movie. Reynolds had previously played a Navajo Indian in the western movie Navajo Joe (1966). Reynolds is of part Cherokee Indian descent.
Part Cherokee Indian, Burt Reynolds plays a Yaqui Indian in this movie. Prior to the making of this film, Reynolds had played characters of Indian descent in two productions of television series. The first was as the half-breed blacksmith Quint Asper in _"Gunsmoke (1955)"_ whilst the other was as the New York DA's office cop Detective Lieutenant John Hawk, a full blooded Iroquois Indian, in Hawk (1966).
Burt Reynolds and Raquel Welch fell out whilst making this movie, three years later they both starred in "Fuzz". However Welch only agreed to do the picture after it was agreed that she would not have to appear in any scenes with Reynolds. They would remain enemies until 1982 when the producers of "Cannery Row" fired Welch claiming she was unprofessional, and replaced her with Debra Winger. Reynolds testified on her behalf stating "Although Raquel and I don't like each other, she was always on time well-prepared and thoroughly professional" she ended up winning $10.8 million.
According to Lorenzo Lamas' wife memoirs - Esther William's biography - during the shooting of the film, Jim Brown defied Lamas to fist fight with him, for fun, so that Brown can prove his physical superiority. But everything went awry for Brown, because Lamas was a karate expert.
Though this movie has often been called a "spaghetti western", it actually isn't. That term is applied to westerns that were filmed by European companies (usually Italian), with a European (usually Italian) cast and crew and shot in Spain, because its terrain closely resembles the northeast Mexico/southwest US area. Although this film was shot in Spain, it was filmed by an American studio (20th Century-Fox) with an American director, producer, writers and mostly American crew. Star Burt Reynolds' previous film, Navajo Joe (1966), would be properly regarded as a "spaghetti western", but not this one.