Rosalind Russell received an Academy Award nomination for her role in this film. Apparently, she was so sure she was going to win that, when the winner was about to be announced, she had risen from her seat to accept it... only to discover that the winner was Loretta Young for her performance in The Farmer's Daughter.
Although billed 9th in the credits, actress Sara Allgood appears only in one scene and does not have one single line of dialogue.
The movie is one of three RKO-distributed films that were edited heavily after their initial unsuccessful first runs; the others were The Devil and Daniel Webster (aka "The Devil and Daniel Webster") and Joan of Arc. All three have been restored to their full length (or, in the case of "Mourning Becomes Electra", approximately their full length) on DVD.
The original Broadway production of "Mourning Becomes Electra" by Eugene O'Neill opened at the Guild Theater on October 26, 1931, ran for 150 performances and was revived in 1932 and 1972.