The George Harrison "Beatles" song "Something (In The Way She Moves)" which is heard in the theatrical and original home videocassette releases of this movie has been removed from its LaserDisc and DVD releases.
This film reunites Walter Matthau and Art Carney, who starred together as Oscar Madison and Felix Ungar in Neil Simon's original Broadway production of "The Odd Couple". However, according to the play's director, Mike Nichols, the two actors had not been friendly at that time, and Matthau had behaved very badly towards Carney in an effort to dominate the rave reviews the play received.
The film is the first of two star teamings of Walter Matthau and Glenda Jackson who starred together again in Hopscotch (1980), due to the success of this film which spun-off a television sitcom.
The name of the central character Dr. Charley Nichols (Walter Matthau) was changed to Dr. Charley Michaels for the spin-off television series House Calls (1979) which ran for fifty-nine episodes across four years and three seasons.
The song that Walter Matthau is attempting to sing in the shower is Cherubino's song from Act II of Mozart's "Nozze di Figaro" (The Marriage of Figaro).