James CagneyJames Cagney was originally offered the role of Alfred Doolittle. When he pulled out at the last minute, it went to the man who played it on Broadway, Stanley HollowayStanley Holloway. Peter O'ToolePeter O'Toole, Cary GrantCary Grant, Noel CowardNoel Coward, Michael RedgraveMichael Redgrave and George SandersGeorge Sanders were all considered for the role of Higgins before Rex HarrisonRex Harrison was finally chosen to reprise his Broadway role. When asked why he turned down the role of Henry Higgins, Cary GrantCary Grant remarked that his original manner of speaking was much closer to Eliza Dolittle.
In her 2004 autobiography "Tis Herself", Maureen O'HaraMaureen O'Hara claimed that [?] Jack L. Warner asked her to dub Audrey HepburnAudrey Hepburn's singing voice in the film.
The title of the film appears nowhere in the dialogue nor any of the song lyrics.
[?] Jack L. Warner paid $5.5 million for the film rights in February 1962. This would set a record for the amount of money paid for the film rights to any intellectual property, broken only in 1978 when Columbia paid $9.5 million for the film rights to Annie.
Amusement park trams were rented to carry ballroom scene extras across the studio lot, in order to prevent their makeup and costumes from getting dirty or damaged.
Audrey HepburnAudrey Hepburn announced the assassination of Pres. John F. KennedyJohn F. Kennedy to the devastated cast and crew immediately after filming the number "Wouldn't It Be Loverly?" on the Covent Garden set on 22 November 1963.
27A Wimpole Street in London (Higgins' address) does not exist (there is a 27 Wimpole Street).
Production designer [?] Gene Allen was never given a budget to work from. He just designed and had built all the sets without having to worry about how much they cost.
Rex HarrisonRex Harrison's microphone (hidden in his neckties) would occasionally pick up police broadcasts from passing police cars.
Jeremy BrettJeremy Brett, who celebrated his 30th birthday during filming, was very surprised to learn that all of his singing was to be dubbed by a 43-year-old American named Bill ShirleyBill Shirley, especially since his own singing voice at that time was remarkably good.