Henry Fonda originally turned down the role of Frank. Director Sergio Leone flew to the United States and met with Fonda, who asked why he was wanted for the film. Leone replied, "Picture this: the camera shows a gunman from the waist down pulling his gun and shooting a running child. The camera pans up to the gunman's face and...it's Henry Fonda" (until then, with one exception, Fonda had only been cast in "good guy" roles. Leone wanted the audience to be shocked).
Al Mulock, who played one of the three gunmen in the opening sequence, committed suicide by jumping from his hotel window in full costume after a day's shooting. Production Manager Claudio Mancini and Screenwriter Mickey Knox, who were sitting in a room in the hotel, witnessed Mulock's body pass by their window. Knox recalled in an interview that while Mancini put Mulock in his car to drive him to the hospital, Director Sergio Leone said to Mancini, "Get the costume! We need the costume!" Mulock, who had appeared as the one-armed bounty hunter in Leone's The Good, the Bad and the Ugly (1966), was wearing the costume he wore in the movie when he made his fatal leap.
Henry Fonda prepared for his role as the villain "Frank" by arriving in Italy with a pair of brown colored contact lenses and a mustache. When Sergio Leone saw them, he ordered them removed. Leone had planned an important close-up shot of Frank's entrance and wanted the audience to instantly recognize Fonda with those blue eyes.
For the opening sequence where the three dusters waited for the train, filmmakers lightly coated the face of Jack Elam with jam and began filming close-ups while letting a fly out of a jar filled with flies, attempting to get Elam's reaction as one would land on his cheek.
This marked the first of the last three films to be fully directed by Sergio Leone. All three of his last films would be edited for U.S. distribution, resulting in box-office failure in the U.S. (although the longer international versions would be successful in other countries). In Italy, an even longer version of the movie was released. It does not exist in an English dubbed version.
The original intent for the opening scene was to use music already composed by Ennio Morricone. However, the attempted blend didn't seem to fit well. The decision was made to drop Morricone's score from the opening train station sequence and record the ambient sounds relating to the scenes (including the squeaking windmill and individual footsteps) after Morricone experienced a musical performance created by using only the sounds of a metal ladder. This created an exaggerated version of what had come to be known as "spaghetti sound".
When Henry Fonda was trying to decide whether to be in this film, he asked his friend Eli Wallach, who had just made The Good, the Bad and the Ugly (1966) with Sergio Leone, if he should take the part of Frank. Wallach said that he had to do it and told Fonda, "You will have the time of your life." (Similarly, it was Fonda, saying he considered Leone one of the greatest directors he ever worked with, who persuaded James Coburn to take the part of Mallory in the second "Once Upon a Time..." film, Duck, You Sucker (1971).)
The main selling point to producers for the use of the Techniscope process was the savings in camera negative; but, another advantage was being able to derive the 2.35:1 aspect ratio while shooting with spherical lenses which avoided the distortion created by anamorphics during certain camera moves and extreme close-ups (such as those used by Sergio Leone). This film, together with The Good, the Bad and the Ugly (1966) (also directed by Leone and shot by Tonino Delli Colli) are now considered masterpieces in the use of the Techniscope system.
Jason Robards, Jr. showed for his first meeting with the director completely drunk, and Sergio Leone threatened to fire him if he ever did that again. Robards was generally well-behaved thereafter, though in June 1968, after receiving word of the assassination of Robert F. Kennedy, he broke down and Leone agreed to stop filming for the day.
Although Lionel Stander's establishment is located in Monument Valley, the interiors were shot at Cinecittà. Cheyenne's men enter with a cloud of red dust. The red dust was imported from the Monument Valley location.
Co-writer Bernardo Bertolucci says on the film's DVD that when he first suggested to Director Sergio Leone that the film's central character be a woman, Leone was hesitant. Leone first budged on this subject by suggesting the introductory shot of Jill would be from below the train platform so the camera could see under Jill's dress and show she wasn't wearing any undergarments. Claudia Cardinale said she was never told this idea, and said she probably wouldn't have agreed to be in the movie if it required this shot (suggesting that Leone, mercifully, gave up on the idea in the writing process).
After completing the Dollars trilogy (Fistful of Dollars (1964), For a Few Dollars More (1965), and The Good, the Bad and the Ugly (1966)), Sergio Leone didn't want to do another western and began working on Once Upon a Time in America (1984); however, after the huge success of the Dollars Trilogy in the U.S. in 1967, Leone wanted to produce films in the U.S., and he began selling the idea for Once Upon a Time in America (1984), but studios wouldn't let him do it until he made another western for them. Eventually, Leone decided to create another trilogy, which began with this movie, developed into Duck, You Sucker (1971) and ended with Once Upon a Time in America (1984). The ''Once Upon a Time'' trilogy, to which it is often referred, is effectively about "three historical periods which toughened America".
Sergio Leone made hundreds of references to films that influenced him. Some were quite obvious (like three men waiting for the train as in High Noon (1952)) and some were very subtle, like the choice of Woody Strode's sawed-off Winchester rifle, similar to the weapon Steve McQueen carried in Wanted: Dead or Alive (1958). McQueen referred to this unique weapon as a "Mare's Leg".
In the opening scene, when Stony (Woody Strode) is under the water tank, water kept dripping onto the brim of his hat, causing him to flinch, and Sergio Leone to stop filming. Leone was going to move Strode but, at the actor's suggestion, kept him in the same spot. Strode wanted his character to be viewed as so cool as to not let dripping water affect him. On the spur of the moment, Leone had Strode take off his hat and drink the collected water.
Sergio Leone liked to tell the story of a cinema in Paris, where the film ran uninterrupted for two years. When he visited this theater, he was surrounded by fans who wanted his autograph, as well as the projectionist, who was less than enthusiastic. Leone claimed the projectionist told him "I kill you! The same movie over and over again for two years! And it's so SLOW!"
Sergio Leone originally wanted Sophia Loren to play Jill McBain, and Carlo Ponti, her husband, was willing to provide a considerable amount of financial backing if she was in the film. However, Leone decided not to cast her because he feared that she would try to gain too much dominance and influence on how the film was made, given her famously headstrong and temperamental personality. He instead cast Claudia Cardinale, a personal friend of his, whom he convinced to play Jill without showing her the script.
Afraid of being typecast having made three spaghetti Westerns in a row with Sergio Leone, Clint Eastwood declined the opportunity to appear in the film. This led to a breakdown in Eastwood and Leone's relationship which was only resolved in 1988 when Eastwood was in Rome promoting Bird (1988) and got a call from his former director. They met for dinner. A few months later, Leone died from a heart attack.
When Cheyenne meets Harmonica early in the story, he reveals Harmonica's gunshot wound (at the time). At the end of the movie, when Harmonica last sees Cheyenne alive, he reveals Cheyenne's gunshot wound.
Claudia Cardinale's first day of filming was her nude love scene with Henry Fonda. This also marked the first time Fonda had done such a scene. His wife insisted on being on-set during the filming of it.
Following the huge success of the Dollars trilogy, United Artists were prepared to finance Sergio Leone's ambitious epic, but only if it featured top box-office names. They put forward Charlton Heston, Gregory Peck, and Kirk Douglas, but Leone balked at the proposed casting, and moved over to Paramount Pictures instead.
This was the first feature to involve Sergio Leone's newly formed company, Rafran, which was named after his two daughters, Raffaella and Francesca. The two young girls appear, uncredited, at the Flagstone station.
Unlike the Dollars trilogy, which were all solely shot in Spain, Sergio Leone travelled to the U.S. to shoot some scenes in the iconic Monument Valley, one of John Ford's favorite locations, making it the first "spaghetti Western" to be shot in the U.S.
The duster coats featured in the film became the must-have fashion items in its day. The French department store Au Printemps had to affix signs to their escalators reminding customers not to let their coats get caught up in the machinery.
The original treatment of the movie was written by Dario Argento and Bernardo Bertolucci, who were friends at the time. They watched a lot of classic westerns and came up with a story that accommodated many of their favorite western scenes.
At the opening duel, Woody Strode carries a "Mare's Leg" firearm (Winchester Model 1892), in a tribute to the Western series, Wanted: Dead or Alive (1958), in which Steve McQueen's bounty hunter used it as a main weapon.
Clocks are a recurring image, many simply painted, or incomplete, reflecting the theme of time noted in the title. In one gun battle, a shooter aims from "five past noon". Another clock is only painted through four (IV). Compare the shadow line at 12:02 with the vertical line of the hanged person late in the film.
Morton, the head of the railroad, desires to see the Pacific Ocean before he dies. He has ridden his special train all the way from the Atlantic. Both oceans are filled with salt. Morton's Salt is the a popular brand of table salt. In Morton's last scene in the film, he lays face down in fresh water, making it, figuratively speaking because of his name filled with salt. It also must be suggested, if he were to ever acquire McBain's "sweetwater" (water without salt), he would be- again- be filling with salt.
Spoilers: The character of "Harmonica" (Charles Bronson) in Once Upon a Time in the West (1968) was influenced by Robert Vaughn as a character who played the harmonica and is a gunfighter in an episode of Zane Grey Theater (1956) in "Courage Is a Gun".