Charles Chaplin re-shot the scene in which the Little Tramp buys a flower from the blind flower-girl 342 times, as he could not find a satisfactory way of showing that the blind flower-girl thought that the mute tramp was wealthy.
Charles Chaplin's first film made during the sound era. He faced extreme pressure to make the film as a talkie, but such was his popularity and power in Hollywood that he was able to complete and release the film as a silent (albeit with recorded music) at a time when the rest of the American motion picture industry had converted to sound.
In terms of years, this film was Charles Chaplin's longest undertaking. It was in production from 31 December 1927 - 22 January 1931, over three years. It shot for only 180 days, though.
At the beginning of the film, a town official and a woman dedicating the statue can be heard uttering nondescript words by way of a paper reed mouth instrument. The sounds were made by Charles Chaplin and this was the first time that his voice was heard on film.
At one point, Virginia Cherrill came back to the set late from an appointment, keeping Charles Chaplin waiting. Chaplin, whose relationship with Cherrill was not friendly, fired her on the spot. He intended to reshoot the film with Georgia Hale, his heroine from The Gold Rush, playing the flower girl; he even reshot the final scene between the tramp and the flower girl with Hale in the role. However, Chaplin had already spent far too much time and money on the project to start over. Knowing this, Cherrill offered to come back to work - at double her original salary. Chaplin reluctantly agreed and the film was completed. (Source: Virginia Cherrill interview, Unknown Chaplin)
Though no footage of Georgia Hale appears in the finished film, the reconciliation scene she shot for him in Virginia Cherrill's absence, has survived.
One of Charles Chaplin's friends, the famous illustrator Ralph Barton, was on set one day during the filming of the scene where Charlie and the blind girl meet. These home movies, which appear in Unknown Chaplin, and is the only known behind the scenes footage of Chaplin at work in costume as the tramp.