The title of the film "M" refers to the fact that when the blind man selling balloons spotted the killer, a gangster wrote an "M"in his palm with chalk , and then pretended to talk to the killer. His hand patted his back and printed "M" on his coat. The original name of the film was "M-Eine Stadt sucht einen Mörder", but it was changed to "M" because the producer was afraid that the Nazis came to the stage and banned the film because of the title. The practice of rigorous underworld organizations and private courts in the film refers to the Nazis before the usurpation of power in 1931.
There was no final judgment scene in the initial version, and the scene was added in the later full version.
