Continuity mistake: When Klink sits down with Marlene, her hands alternate between being on his face to behind his neck and back between shots.
Continuity mistake: As Schultz marches in with the Kraut platoon, he reports to Klink. As he goes to stand at attention and report, the new tunnel section he's over collapses, and he completely disappears into the hole. The camera goes to a close up on Klink, then back to the hole, and you see Schultz standing in the hole and it's only chest deep.
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