In the opening scene, Red Reddy repeats "Heinie Manush" to the rhythm of the motion of the train he's riding and gradually the other passengers begin to repeat it as well. Henry "Heinie" Manush was a major league ballplayer who played for 17 seasons (1923-1939) and had retired from baseball at the time this film was made. He had a .330 career batting average and was inducted into the Baseball Hall of Fame in 1964.
Edmond O'Brien replaced James Craig in the role of "Red" after he was re-assigned to appear in Unexpected Uncle (1941).
First film for Ruth Warrick under her new contract at RKO. She had initially gone to the studio the previous year with Orson Welles to make her film debut in Citizen Kane (1941).
This is one of the earliest examples of a movie ending with the lovers on a train entering a tunnel; the most famous version of this phallic gag is, of course, North by Northwest (1959).
According to a contemporary article in the Los Angeles Times, Anne Shirley was considered for the female lead in this film.