Clint Eastwood's contract for Rawhide (1959) prohibited him from making movies in the United States while on break from the series. However, the contract did allow him to accept movie assignments in Europe.
Since all of the footage was filmed silently, Clint Eastwood did not add his voice to the soundtrack until 1967, when the movie was prepared for U.S. release.
Sergio Leone warmed to Clint Eastwood very quickly and joked that he had only two expressions: with hat or without hat.
Originally called "The Magnificent Stranger," the title wasn't changed to "A Fistful of Dollars" until almost three days before the movie premiered in theaters. In fact, nobody had bothered to inform Clint Eastwood of the change, and as a result, Eastwood remained virtually unaware of the positive buzz surrounding the movie until an agent pointed it out to him in a Variety Magazine article three weeks later.
This movie is a remake of Le garde du corps (1961), which itself was based on the as yet unadapted 1929 novel "Red Harvest" by Dashiell Hammett. In fact, this movie's U.S. release was delayed when Yojimbo screenwriters Akira Kurosawa and Ryûzô Kikushima sued the filmmakers for breach of copyright. Kurosawa and Kikushima won, and as a result received 15% of this movie's worldwide gross and exclusive distribution rights for Japan, Taiwan, and South Korea. When Kurosawa released the film in Japan, he pointedly retitled it 'The Return of Yojimbo.' Kurosawa said he made more money off of this movie than he did on Le garde du corps (1961).