According to Rosemary Clooney, the "midnight snack" scene in which Bob Wallace expounds on his theory of what foods cause what dreams was almost entirely improvised.
According to Rosemary Clooney, Bing Crosby and Danny Kaye's "Sisters" performance was not originally in the script. They were clowning around on the set, and director Michael Curtiz thought it was so funny that he decided to film it. In the scene, Crosby's laughs are genuine and unscripted, as he was unable to hold a straight face due to Kaye's comedic dancing. Clooney said the filmmakers had a better take where Crosby didn't laugh, but when they ran them both, people liked the laughing version better.
For the song "Gee, I Wish I Was Back In The Army," there is the lyric, "Jolson, Hope And Benny all for free." This is a reference to three wartime entertainers: Al Jolson, Bob Hope and Jack Benny. The original words were "Crosby, Hope and Jolson all for free," but the lyric was changed because with Bing Crosby in the cast the original lyric would break the fourth wall.
Third of three films to feature Bing Crosby singing "White Christmas." The other two are Holiday Inn (1942) and Blue Skies (1946).
In an interview, Rosemary Clooney once quipped that this could have been a near-perfect movie if only they could have "dubbed" her dancing.