This was actually the last episode of The Rockford Files to be filmed (unintentionally; another ten episodes were supposed to be filmed after this).
In this episode, Col. John "Howling Mad" Smith, tells that Jim had a nickname when he was in the military; Sgt. Jim "Hound Dog" Rockford.
W.K. Stratton had played sergeant Frank Dusenberg for a couple of episodes, partnered up with Dennis Becker. In both those episodes, he kept shirking his duty, because his wife, Dory, was expecting. In this episode, he plays (the totally unrelated) agent, Whipple, who's wife's also expecting.
Colonel John "Hannibal" Smith and Captain "Howling Mad" Murdock were characters on The A-Team television series (1983-1987), created by Stephen J. Cannell, one of the creators and producers of The Rockford Files. Combine those names in the character of Colonel John "Howling Mad" Smith in this episode.
This episode, "The Hawaiian Headache," features three character actors (Ken Swofford, W.K. Stratton and Christopher Cary), each of whom played entirely different roles in other episodes of The Rockford Files. In fact, Swofford and Cary shared screen time in an earlier episode ("The Queen of Peru"). Swofford went from a hapless tourist in "Peru" to Jim Rockford's old Army commander in "Headache." Cary played a ruthless mobster in both.