The original cut was nearly four hours long. Over two hundred hours of footage was shot.
To prepare for his role, Robert Downey Jr. learned how to play the violin and tennis left-handed. He also engaged a coach to help him imitate Charles Chaplin's posture and mannerisms.
In an interview on Inside the Actors Studio (1994), Robert Downey Jr. said that while preparing for the movie, he watched all of Charles Chaplin's movies. When asked how he felt about them, he said, "They scared the hell out of me."
Geraldine Chaplin recalled that when she first saw Robert Downey Jr. in full costume, she was so awestruck on how much he resembled her late father that she needed a moment to collect her thoughts to even speak.