The Kamikazes Are Coming - S6-E20
Factual error: When Hockstetter shows up in Klink's office he has two SS soldiers with him. One has a coat on with a general's rank insignia.
The Kamikazes Are Coming - S6-E20
Revealing mistake: As the rocket blasts out of the recreation hall, the guide wires for the model are visible.
The Kamikazes Are Coming - S6-E20
Other mistake: As Marya comes out of camp office, the seams between the sections of the studio flooring are visible at the bottom of the shot.
The Kamikazes Are Coming - S6-E20
Continuity mistake: When Otto and the Russian go to leave there's another man with a blue hat by the door. When the angle changes, there's suddenly a German guard standing behind him.
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