There have been a number of comparisons made between Modern Times and Chaplin's earlier pictures. For one thing, the plot device of the Tramp befriending girls who were either homeless or badly down on their luck had been used in such films as The Vagabond (1916), The Circus (1928), City Lights (1931), and later Limelight (1952).

Critics at the time (and since) have noted how many of the episodes in this film are similar to earlier Chaplin works: The Rink (1916), with its daredevil roller-skating ballet; The Floorwalker (1916), which also includes a scene of Charlie's difficulties with an escalator; and Easy Street (1917), in which he also battles criminals.

A resemblance has been noted between the factory boss's surveillance of his employees and his instructions to them via a giant screen and the video system later used by Big Brother in George Orwell's Nineteen Eighty-Four.

The main melody Chaplin wrote for Modern Times had lyrics added to it in 1954 by John Turner and Geoffrey Parsons; that's when it became known as "Smile." Nat King Cole recorded it and had a #10 hit on the Billboard charts that year. The lyrics ("Smile though your heart is aching/Smile even though it's breaking/When there are clouds in the sky/You'll get by") were no doubt inspired by the final moments of the film when Charlie tells the Gamin, "We'll get along," and enjoins her to smile. The song has been covered by such diverse performers as Michael Bolton, Eric Clapton, Lyle Lovett, Diana Ross, Tony Bennett, Jimmy Durante, and many others.

Robert Downey, Jr., who was Oscar®-nominated for playing the actor-director in the biopic Chaplin (1992), recorded "Smile" on his 2004 CD release "The Futurist."

In addition to Chaplin's own composition and his uncredited use of the melody of the French ditty "Titine," the score of Modern Times includes snippets of the popular songs "Hallelujah, I'm a Bum," "Prisoner's Song," "How Dry I Am," and "In the Evening by the Moonlight."

Chaplin's score for Modern Times was performed in the mid-1930s by the Philadelphia Philharmonic Orchestra under the title "A Modern Symphony."

The similarities between Modern Times and the French release À nous la liberté (1931), in which writer-director René Clair also satirized the mechanization of work and society, led to a lawsuit of more than a million dollars brought by the film's production company, Tobis, against Chaplin. The suit, however, was not supported by Clair, who insisted he had been strongly influenced throughout his career by Chaplin and was flattered that the great film artist would borrow from him.

by Rob Nixon