Watch the Trains Go By - S4-E19
Continuity mistake: As Schultz is by the car, Hogan is behind the fire brigade equipment. When Klink calls Schultz, Hogan gets up from behind the equipment. A second later, in a closeup, he comes up from behind the equipment again.
Answer: Nimrod's actual identity was never revealed in the series. It was only known that he was a British intelligence agent. Nimrod was not Colonel Klink. Hogan had only implied it was him as a ruse to get Klink returned as camp commandant, not wanting him replaced by someone more competent who would impede the Heroes war activities. (As another contributor previously posted, the term "nimrod" is slang for a nerdy, doofus type of person, though it's unclear why that was his code name).
raywest ★