Irene Dunne worked with dialect coach Judith Sater for two months to perfect her Norwegian accent. Dunne became so immersed in getting her character's voice down that she used the accent around her home with her family.
Despite garnering the best reviews of any RKO film released in years, the movie failed to turn a profit due to its high production cost ($3.068 million). It spawned the CBS TV series Mama (1949) that ran from 1949-57.
The play was produced on Broadway by Richard Rodgers and Oscar Hammerstein II. The film's producers purchased the rights for $2500 for each week of the play's run, up to $150,000, on the condition that the film would not be made until the play closed. The stage version ended up running for nearly two years. The original Broadway production opened on October 19, 1944 at the Music Box Theater and ran for 713 performances with a cast that included Marlon Brando in his Broadway debut.
Greta Garbo turned down the role of Martha around the same time she also rejected the lead in Alfred Hitchcock's The Paradine Case (1947). She is reputed to have commented, "No murderesses, no mamas."