One actor who played Don Quixote on stage was José Ferrer. Peter O'Toole worked with Ferrer in Lawrence of Arabia (1962), and even said that he learned the most about acting from the brief time he spent with Ferrer.
Peter O'Toole recorded his vocal tracks for the film, but realized that his own singing voice was not good enough for the requirements of the music, so he assisted in the search for a voice double. The man O'Toole picked sounded nothing like him, so a new search was begun, and eventually Simon Gilbert was selected as the singing voice of Don Quixote, because his singing voice sounded the most like O'Toole's speaking voice.
A song called "To Each His Dulcinea" was omitted from the movie. It was sung by the Padre in the stage play and featured the lines, "A man can do quite anything, / Outfly a bird upon the wing / Hold moonlight in his hand."
This was one of the last films to receive a limited-release, reserved-seat "roadshow" engagement prior to its general release. Lost Horizon (1973) was the last of the "big film musicals" to receive this kind of release during the time period.
All of Aldonza's songs were either slightly altered or cut. "It's All The Same" was presented complete but had a few of its lyrics rewritten by Joe Darion. The song "Aldonza" had two of its verses cut, so that the version heard in the film begins with the verse "For a lady has modest and maidenly airs . . . " The second verse of the deathbed reprise of "Dulcinea" was left out of the film, and the song "What Does He Want of Me", which Aldonza sings (in the stage version) after receiving Quixote's "missive", was completely omitted.
One of only five big budget screen adaptations of Broadway musicals filmed between 1955 and 1973 to be presented in the 1.85:1 screen ratio (the others were The Pajama Game (1957), Damn Yankees! (1958), Cabaret (1972) and Hair (1979)). Most of the others were presented in the wider Cinemascope, Todd-AO, Technirama, or Panavision ratios. The film was, however, blown up to the typical Todd-AO ratio (2.20:1) for its roadshow presentations.
Peter O'Toole was not at all happy about the firing of his friend Peter Glenville as director, as he liked the helmer's idea of making the film a non-musical. O'Toole was deliberately difficult with Glenville's replacement, Arthur Hiller, referring to him as "Little Arthur" throughout production.
The original creators of the show - Dale Wasserman (author), Albert Marre (director) and Mitch Leigh (composer) - were all originally hired by United Artists to work on the film, but UA was unhappy with the screen tests they made, so they were all dismissed and director Peter Glenville was called in. But when UA discovered that he planned to eliminate most of the songs, he was also dismissed. UA then rehired Wasserman, and added Saul Chaplin and producer-director Arthur Hiller, who retained most of the musical's score for the film. However, the "look" of the film, according to Chaplin, had already been largely determined by the previous creative teams hired to make the movie. It has always remained unclear who cast the usually non-singing actors (such as Sophia Loren, who sang in the film, and Peter O'Toole, whose singing was dubbed), and which creative team cast the singing actors (Julie Gregg, Gino Conforti, James Coco and several of the "muleteers").
Although no new songs were written for the film, the incidental music, while based on the songs, is not an exact transcription of the incidental music for the original stage musical, as it is, for example, in Show Boat (1936).
While Peter O'Toole was generally slated for his "singing" performance in the film, what many critics chose to overlook was the fact that this was not O'Toole's first musical. Indeed, his appearance in Herbert Ross' musical remake of Goodbye, Mr. Chips (1969) netted the actor his fourth Best Actor Academy Award nomination.
The original stage production opened at the ANTA Washington Square theater in New York City on 22 November 1965, moved to Broadway after a short run, and eventually had a total of 2329 performances. The cast featured Richard Kiley, in the role of Don Quixote, who won the 1966 Tony Award for Best Actor in a Musical. "Man of La Mancha" won the 1966 Tony Awards for the Best Musical and Best Score.