Revealing mistake: LeBeau hands Schultz the pan straight from the hot plate, but Schultz puts at least three fingers around it while eating without any apparent issues. Note that LeBeau earlier said the Crepe Suzette were "not quite ready yet" - or in other words, still cooking. (00:01:40)
Continuity mistake: When Klink does a walk through in the barracks, he turns to face Hogan in front of Schultz. As he does, the end of his riding crop pushes against Schultz's lower chest and sticks. When the camera cuts the crop is free and well clear of Schultz.
Continuity mistake: Major Bonacelli goes to put his hand in his coat for money, he pauses with it in for the next few lines. When Newkirk asks about Germans eating a lot of pizza, Bonacelli's hand is suddenly out and gesturing.
Continuity mistake: Newkirk holds takes Schultz's rifle so Schultz can play in the game. On Schultz's second hit, you see Newkirk clapping. In the close up, you see Newkirk's hands firmly on the butt of the rifle. Also, Newkirk is holding the rifle with the muzzle in the dirt. This would put a plug of dirt into it, but when Klink takes it away, you can see that the muzzle is clean and clear.
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