Because John Garfield was playing a Mexican general in Juarez (1939) when Julius J. Epstein and Philip G. Epstein were writing the screenplay to this movie, they made his character Hispanic as a joke.
This film is often mistakenly considered a sequel to Four Daughters (1938) since it has the same primary cast (Claude Rains, John Garfield, Jeffrey Lynn, May Robson, Frank McHugh, Dick Foran, Gale Page, and the real life Lane sisters - Priscilla Lane, Rosemary Lane and Lola Lane - all in somewhat similar roles, most specifically Page and the Lanes portraying four sisters to Raines' father) and even the same director, Michael Curtiz, but technically is not - the actors play different characters in this film than in the earlier film. Four Wives (1939) and Four Mothers (1941) are true sequels to Four Daughters.
The play "Fly Away Home" (on which this film is based), written by Dorothy Bennett and Irving White, opened in New York on 15 January 1935. It starred Thomas Mitchell, Andrea King (billed as Georgette McKee), Sheldon Leonard, Albert Dekker, Philip Faversham, and featured Montgomery Clift in his professional debut.