Hey Hey in the Hays Office: Sex, (Christian) blasphemy, and violence were explicit targets of the written Production Code, and they make great marketing for pre-Code film festivals. But the individuals responsible for implementing the Production Code also took care to safeguard such American family values as racism and antisemitism.

On The Story of Vernon and Irene Castle, 1939

The original plan was to show Astaire and Rogers accompanied by black musicians, to represent the orchestras of Jim Europe and others who often worked with the Castles. The idea was scrapped, however, when Hollywood's censorship office gratuitously pointed out to RKO that this would "give serious offense to audiences throughout the sourthern part of the United States... and your studio is likely to be deluged with protests." A similar admonition was wired from RKO's New York office: ".... strongly advise use of white men. No one remembers or cares which they used and we should not take chance with colored."

-- John Mueller, Astaire Dancing

On Three Comrades, 1938

... many changes between the original script and the final one were requested by the Hays Office before approval was granted.... no use of the Nazi emblem or mention of specific German leaders were to be used; a scene in which a bookburning takes place had to be removed; a "We are Jews" speech delivered by the character Dr. Becker was to be deleted; some additional lines of dialogue, situations and character names concerning Jews were to be deleted.... Additionally, suggestions were made to change the setting of the film from the 1930s to two or three years after the end of World War I. According to a 27 Jan 1938 letter sent to Louis B. Mayer by Joseph I. Breen, PCA director, the Hays Office suggested, "It might be better to make the Communists the 'Heavies'... do not indicate by emblem or uniforms that the period is other than following the war." Another suggestion offered by Breen was to delete a reference to Felix Mendelssohn.

-- The American Film Institute Catalog, Feature Films, 1931-1940

Much of the crew from Three Comrades reassembled two years later to make The Mortal Storm, which was able to attack the Nazis openly -- albeit with a blanket substitution of the term "non-Aryan" for "Jewish."