Bing Crosby originally wanted Frank Sinatra to play the part of Tony Vincent, eventually played by Robert Wagner.
When Debbie Reynolds auditions doing a duet with Robert Wagner at his nightclub, the trumpet player in the yellow shirt sitting behind piano player Ray Walston is Herb Alpert, who later had such a successful career that he was able to form his own label, A&M Records.
The haunting main title theme, heard under the opening credits, was composed by Alfred Newman and first heard in the mountain retreat sequence of The Razor's Edge (1946).
Bing Crosby started playing priests in "Going My Way" (1944). In this movie he is reteamed with actor Frank McHugh, who also played a priest in "Going My Way".