Visible crew/equipment: As Hogan, Le Beau, Kinch, and Schultz talk at the car, the boom mic is reflected in the chrome and on the hood.
The Antique - S5-E12
Visible crew/equipment: When Burkhalter first comes into the office, the camera rolls a little closer. As it does, you can see the shadow of the camera on Burkhalter's arm.
Visible crew/equipment: As Klink and Schultz approach the barracks where Le Beau is "weightlifting", there is a cord or cable along the ground that would be for studio equipment.
Visible crew/equipment: As Burkhalter is talking to Strauss and Klink in front of the office door, you can see the shadow of the boom mic moving over each as they talk.
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