An electrician for Warner Bros. studio came up to Paul Muni after an advanced screening of the film and told him that his 9-year old son asked him to buy him a microscope because of Muni's performance. Even though he went on to win the coveted Oscar Muni said that this was the greatest compliment he had ever received and that all other accolades meant nothing compared to that compliment.
Hal Wallis originally rejected Sheridan Gibney's script. Wallis wanted the movie to be a college romance. The star, Paul Muni, had script control in his contract, so the actor wrote across the top of the screenplay, "I approve this script as written." Warner Bros. had to film Gibney's original script, which went on to win an Oscar. From "Film Crazy" by Patrick McGilligan, St. Martin's Press, 1983; and "Actor: The Life & Times of Paul Muni" by Jerome Lawrence, 1974.
After playing a series of hard-bitten roles in films like Scarface (1932) and Black Fury (1935), Paul Muni lobbied hard for a change of pace. Jack L. Warner, head of Warner Brothers, wasn't keen on his star taking such a change of direction but eventually relented, effectively opening up a tidal wave of biopics that became the mainstay of Warner Brothers' output in the late 30s and early 40s.