Cary Grant said that this was his personal favorite film.
Leslie Weston was booked to play a taxi driver but withdrew his services and was replaced.
The casting of Cary Grant and Ingrid Bergman as slightly older and wiser lovers had greater relevance to 1958 audiences. Grant was on the third of his five marriages, while Bergman had ridden the waves of scandal following her adulterous relationship with Italian director Roberto Rossellini.
The New York setting of Norman Krasna's original play was substituted for London.
The original Broadway production of "Kind Sir" by Norman Krasna on which the movie is based opened at the Alvin Theater on November 4, 1953, ran for 166 performances and closed on March 27, 1954. The cast included Charles Boyer and Mary Martin in the Cary Grant and Ingrid Bergman roles.
When the censors had a problem with Cary Grant and Ingrid Bergman in a scene in bed together, director Stanley Donen shot an overhead split screen sequence showing both stars side by side in bed, but with a clearly visible "border" between them.