This is what Giusti has to say about it
(To Phil: I added a note, I wasn’t sure about a certain term and consulted a native speaker, who came up with this explanation)
It (the film) was directed by the old Antonio Romàn, a Spanish director, who showed little affinity with the western genre. For this reason Fulvio Lucisano added a second director to the team, Mario Bava, who is said to have solved some of the problems Romàn had in regard to special effects, western action and choice of scenery*. Romàn had been a major director during the Franco regime, ever since the second half of the ‘40s; he had even written the script for a production called Raza, based on an idea suggested by Franco himself. It wasn’t easy to persuade him to accept help. Apparently an agreement was made, that he would be involved in one Bava and Lucisano’s other projects of the same year: he co-wrote Bava’s Terrore nello Spazio (or at least put his name under the script).
(…)
Fulvio Lucisano says the film was almost completely directed by Bava, but the actors have other recollections. Aldo Sambrell thinks Roman was the only director, and this is also how Renato Rossini thinks about it: “Bava did second unit direction, and also did some action scenes; he supervised more or less the whole thing, but Roman was the one who actually directed the movie. I had heard rumours that he was a good friend of Franco’s. His wife, Ivonne Bastien, co-executively produced the movie.”
(…)
Lamberto Bava gives some further explication: “Lucisano called for my father to solve some problems regarding scenery* and costumes, and I went with him to Spain. Tony Roman, this Spanish director, was a nice guy. We had a lot of fun when we found out how he proceeded on the set. He was always very happy with the first take, but then changed his mind and did the same scene over and over again. In the end he inevitably preferred the first take after all.”
(…)
In the contemporary press, Giornale dello Spectacolo, Ringo de Nebraska was first announced as “First unit direction Anthony Roman, second unit direction Mario Bava”, later only Roman was mentioned as director, and the magazine finally opted for “Directed by Anthony Roman, co-directed by Mario Bava”
Note:
- The Italian term ‘fondali’ used by Giusti, may also refer to studio sets
I haven’t scene the film, but if some studio sets were used, they were probably conceived by Bava