Bing Crosby had wanted Deanna Durbin to costar in this picture and also in his next vehicle for Paramount, A Connecticut Yankee in King Arthur's Court (1949). Miss Durbin, about to retire from the screen with the finish of her Universal-International contract on August 31, 1949, declined both offers from Bing. In place of Miss Durbin, Universal loaned Ann Blyth to Paramount for the first Crosby picture.
The acronym "IRA" (a common acronym for the Irish Republican Army) can be seen etched into the background over Ann Blyth's right shoulder at about 3 minutes and 55 seconds into the film. A few minutes later, the letters "RA" can be seen over Bing Crosby's right shoulder when he is in the jail. Presumably the "I" is hidden in the latter scene.
Ann Blyth's trained soprano is barely utilized in this film, as the musical weight is primarily carried by Bing Crosby. Blyth's singing career took an odd trajectory. After her first splash in Mildred Pierce (1945), she was considered a dramatic actress with occasional forays into romantic comedy and adventure roles. Despite the fact that she appeared in several musicals during her tenure at Universal, it wasn't until she shifted to MGM that her singing voice was used to full advantage. At this point, Blyth emerged as a full-on musical star, appearing in The Great Caruso (1951), The Student Prince (1954), Rose Marie (1954) and Kismet (1955). The final irony came when her singing voice was dubbed by Gogi Grant in The Helen Morgan Story (1957) because Warner Bros. felt a strong belter was more appropriate for a torch singer - despite the fact that Morgan herself possessed a gentle soprano much like Blyth's.