Continuity mistake: When the man and woman from the underground meet Hogan at the Hoffbrau, they're taking off their outer coats. The man takes off a dark brown coat and drops it. Hogan picks it up, hands it to the guy who hangs it up. The man removes his dark brown overcoat revealing a tan coat. The next shot, he"s taking off the dark brown coat again, hangs it up and goes for beer.
Continuity mistake: In Klink's quarters, As Schultz and Klink talk, Klink asks a question and takes a bite of steak, and the fork is still up. After the angle change, the fork is suddenly missing.
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. The term "nimrod" is also slang for a nerdy, doofus type of person, though it's unclear why that was his code name.
raywest ★
"Nimrod" is originally a king and hero mentioned in the Tanach and taken into the Bible and the Koran. His name is often used in the sense of "stalker," "hunter," and sometimes figuratively as "womanizer" as in "hunter of women." I've never seen it used to denote a nerdy person, and although I cannot disprove that connotation, I think given his role, the traditional meaning is more likely the intended one.
Doc ★
It's widespread enough that Wikipedia has an entire section on it: https://en.wikipedia.org/wiki/Nimrod#In_popular_culture