During press for this film, Marlo Thomas did an interview with Phil Donahue on his show Donahue (1967). According to her, there was "instant spark" between them. They married in 1980.
Charles Grodin directed the Broadway production but did not appear in it. For the film version, he took over the male lead role but did not direct the film.
Most of the cast of the Broadway production of this play continued on to the film, though Richard Mulligan as Martin was replaced by Charles Grodin. Grodin had produced and directed the play, though did neither for the film.