Trivia

Lee Van Cleef claimed to be faster on the draw than Clint Eastwood. Eastwood could draw, cock and fire in 0.45 of a second, while it took van Cleef only 0.125 second.
--Source: Once Upon a Time in the Italian West: The Filmgoers' Guide to Spaghetti Westerns, Page 46

Sergio Leone wanted Henry Fonda, Charles Bronson or Lee Marvin as his colonel, but their unavailability led to Lee Van Cleef. Leone “His glare makes holes in the screen”.
--Source: Aim for the Heart: The Films of Clint Eastwood, Page 8

Total kill count: 30. (Two of the kills were heard, but not shown.)

The title of the film reportedly originated out of spite towards Jolly Films, the producers of A Fistful of Dollars, with whom 'Sergio Leone' had a bitter falling out.

Clint Eastwood's character calls Lee Van Cleef's character "old man", while Van Cleef's character calls Eastwood "boy". In reality Clint was already 35 and Lee only 40 when this film was made.

Sergio Leone also considered Robert Ryan for the role of Col. Mortimer, being a fan of his performance in The Naked Spur (1953).

"Monco" is NOT the same character as "Joe" in Per un pugno di dollari (1964). This was the finding of an Italian court that adjudicated the lawsuit brought by Jolly Films, producer of "A Fistful of Dollars". After the release of the first film, director Sergio Leone had a falling out with the producers and made this sequel with a different producer, 'Alberto Grimaldi'. Jolly Films sued, claiming ownership of the "Joe" character, but lost when the court decided that the western gunfighter's persona, characterized by the costume and mannerisms, belonged to the public domain's folklore.

Although Clint Eastwood's poncho was never washed during the production of the "Dollar" trilogy, it was mended. In the final scene of Per un pugno di dollari (1964), the poncho is pierced by seven bullets from Ramon's Winchester. In the sequel, Eastwood wears the same poncho back-to-front and the mending of the bullet holes is clearly visible in several scenes. The mended area, originally on the left breast, is now worn over the right shoulder blade.

Sergio Leone originally wanted Lee Marvin for the role of Douglas Mortimer, but when the actor asked for more money, Leone replaced him with Lee Van Cleef.

Aldo Sambrell's character name "Cochelio" is the English spelling of the Spanish word "cuchillo", which means knife.

The safe that Indio robs with his gang in El Paso contains Confederate dollar notes.

The Man With No Name (Clint Eastwood) calls himself Manco in this film. "Manco" is Spanish for "lame of one hand", "one handed" or "one armed", which is pretty appropriate considering his habit of fighting, drinking, etc with his left hand only. His right hand always remains on his gun underneath his trademark poncho. (The assertion that his name is Monco is baseless, as that Italian word has nothing to do in Spanish-speaking towns of the South West of America.)

On its 1969 re-release it was double-billed with Per un pugno di dollari (1964) (A fistful of dollars).

Gian Maria Volonté played two different roles in this movie and it's sequel Per un pugno di dollari (1964) (A Fistful of Dollars). In the original, he played Ramon Rojo and in this movie he played El Indio.

Final film of Joseph Egger.

Director Sergio Leone did not want to make a sequel to Per un pugno di dollari (1964), but it was such a huge hit that Jolly Film--the production company--refused to pay Leone what it owed him from that film unless he made a sequel to it.

Sergio Leone wanted Henry Fonda for the role of Col. Mortimer, but Fonda turned it down. Leone next approached Charles Bronson, who wasn't interested, and Lee Marvin, who refused it because he had just signed to make Cat Ballou (1965). It was then that Leone offered the role to Lee Van Cleef, who hadn't worked in films since How the West Was Won (1962), although he had worked fairly steadily in television. Van Cleef thought that Leone only wanted him for a few scenes, and was astounded when he discovered that he was actually to be the co-star.

The name the Eastwood character was given (in the script, and twice in the film itself), is Monco (in the original Italian version of the film), or Manco (the Spanish equivalent, which is used in English-language versions). In either language, the word means maimed or mutilated, specifically one-handed.