Special permission had to be granted from the Hays Office in order to retain the famous miscegenation (interracial marriage) sequence in the movie. Miscegenation was banned as a film subject, and had been excluded from Show Boat (1929).
The song "Ol' Man River", as performed by Paul Robeson in this film, was #24 on the 2004 American Film Institute's list of the top 100 songs featured in films.
Paul Robeson was the valedictorian of his graduating class at Rutger's College in 1919. He then earned a law degree from Columbia University in 1922 and was admitted to the New York bar, but he never practiced law. The acting bug bit him and led to an acting and singing career in the theater and films.
In the scene in which Paul Robeson sings "Ah Still Suits Me", Queenie (Hattie McDaniel) has a box of Aunt Jemima pancake mix on her work table. It's a subtle nod to Tess Gardella (stage name "Aunt Jemima"), who created the role of Queenie in the 1927 Broadway production.