Background
Following the financial success of A Fistful of Dollars in Italy, several scripts that had been written to capitalize on the popularity of Westerns made by Karl May, but had initially been shelved, were put into production. These films, which featured characters like Django, Ringo and Sartana, would form the Italian Western. With the success of Duccio Tessari's Ringo films in 1965 (A Pistol for Ringo and The Return of Ringo), a wave of films with the name "Ringo" in the title were released, with nearly 30 made between 1965 and 1972, such as 100.000 dollari per Ringo and Ringo and His Golden Pistol. These films rarely had anything to do with the original two films, and were so named to take advantage of their popularity. Savage Gringo was among these films, as its original Italian title was Ringo del Nebraska; the protagonist's name was changed from "Nebraska" to "Ringo" through post-production dubbing.
Directorial credit dispute
The film was originally set to be directed by Antonio Román under the title of Nebraska il pistolero, but after a few days of shooting in La Pedriza in Spain, producer Fulvio Lucisano felt the director "wasn't working out" and halted production. On returning to Rome, Lucisano met with Mario Bava (with whom he had made Bava's most recent film, Planet of the Vampires), who agreed to finish the film, leading to it being completed at Elios Film Studios in Rome. The onscreen credits still include the originally-contracted cast and crew, although Lucisano stated that Bava directed most of the film.
In an interview with the Italian magazine Nocturno, actor Renato Rossini stated "I know this film very well, but I really can't remember Mario Bava involved in it. The director was a Spaniard, Antonio Román, a rather old man, a tall one. [...] We shot it almost entirely in Spain. I was on the set from the first day to the last day, but I really can't remember Mario Bava there." Bava biographer Tim Lucas has suggested that Rossini only had a small role in the film, which would not have required him to be on-set every day.
Mario Bava's son Lamberto Bava was an assistant director on the film, and recalled that Lucisano called his father to do some work on the film, such as matte paintings. Lamberto also noted that he and his father often laughed between themselves at Román's directorial style, as he would always use the first take of each scene. Lamberto Bava's recollections of Román's working methods would have resulted in Lucisano getting Bava to direct. Lucas also notes that Lamberto Bava would not have served as an assistant director if the film had been entirely shot in Spain.
In his study of Spaghetti Westerns, filmmaker Alex Cox considers Anthony Román to be the film's primary director and that Bava served as its second unit director. Film historian Troy Howarth declared that Bava directed about 99% of the film and supervised the editing process as well after the producer fired Antonio Roman.