Dean Martin still had four pictures left in his old contract with producer Hal B. Wallis with whom he hadn't worked after his break-up with Jerry Lewis. Wallis refused to raise Martin's salary, but the star was interested in playing a more serious part and accepted the role of Maury in this picture. After Career, Martin made three more pictures with Wallis: All in a Night's Work, The Sons of Katie Elder and 5 Card Stud.
Carolyn Jones was originally cast as "Sharon Kensington" but switched roles with Shirley MacLaine in order to play Shirley Drake because she wanted the less flamboyant role.
Bette Davis was originally sought for the part of "Shirley Drake" and William Holden was considered for "Maurice Novak" (The Hollywood Reporter, 1958).
Prior to the release of this movie, a fan had written to 'Screen Stories' magazine, inquiring as to what movie Dean Martin would next be appearing in. The response was that one of the movies would be 'Korea' - but there was no mention of 'Career'. While the movie does have a brief character introduction set during the Korean War, Dean Martin never appeared in a movie called 'Korea'.
The film-within-a-film is titled "War Devils".