This was F. Scott Fitzgerald's only screenwriting credit. Fitzgerald's first draft of the screenplay was completed September 1, 1937.
Producer Joseph L. Mankiewicz altered the film's plot to feature an anti-Nazi theme. Joseph Breen, the administrator appointed to enforce the Motion Picture Production Code in Hollywood, objected to the presence of this anti-Nazi theme. Breen insisted the German street thugs should be identified as Communists. When Mankiewicz threatened to quit the production, Breen relented.
According to Gore Vidal's essay in "The New York Review of Books" (May 1980), F. Scott Fitzgerald and his spouse Zelda Fitzgerald had divergent opinions regarding the film's quality. After viewing the final cut, Fitzgerald wrote his sister-in-law and declared: "Three Comrades is awful. It was entirely rewritten by the producer." In contrast, Zelda viewed the film upon its release in 1938 and effusively praised the movie in a letter to her husband.
Prior to production, actress Margaret Sullavan declared that F. Scott Fitzgerald's dialogue was impossible to recite. As a result, producer Joseph L. Mankiewicz and screenwriter Edward E. Paramore Jr. rewrote most of the screenplay's dialogue.
Upon its release, the film was banned in Romania on November 14, 1938, for allegedly promoting "pacifistic tendencies" and "communistic ideas." The film was also banned in Poland until May 12, 1939, when the ban was repealed on the condition that future prints shown in the country delete all scenes and dialogue advocating pacifism.