The series actually had three theme songs. But two of them are only rarely heard. The series opened with a Stu Phillips theme which was quickly yanked, although it continued as background music at the end of many shows. About eight shows into the second season, Ed Sauter wrote a theme that appeared exactly once. For all other episodes, first-season executive producer Glen A. Larson wrote the theme (his first official theme song, not counting "McCloud" which is not credited to anyone).
The title refers to the actor James Caan whom at the time of airing of this script was most famous for his roles in "Brian's Song (1971) (TV)' and The Godfather (1972).