The Flame Grows Higher - S1-E31
Visible crew/equipment: Toward the end of the episode, after the two women are taken out by the Gestapo, Shultz, Hogan, Lebeau, and Newkirk are standing having a drink. The camera goes in for a close-up on Shultz, there is a noticeable shadow of the camera on Shultz's coat, and right arm.
Visible crew/equipment: As Hogan and Le Beau crawl through the car and shut the door, the camera rig, equipment, and cameraman are reflected in the window.
Visible crew/equipment: As Klink gives the info on the Tiger tanks, in the close ups, the studio light is reflected in his monocle.
The Informer - S1-E1
Visible crew/equipment: As Burkhalter looks down at the floor under the water tower, the studio lighting positions are distinguishable on the visor of his cap.
Movies Are Your Best Escape - S1-E8
Visible crew/equipment: When the staff car is entering and coming to a stop in the compound, the reflection of the crew member, camera and lighting rig can be seen in the chrome of the radiator.
Go Light on the Heavy Water - S1-E9
Visible crew/equipment: When the staff car entering the compound stops, you can see a reflection of the crew member stopping the car, the light rig, and the camera in the chrome.
Happy Birthday, Adolf - S1-E17
Visible crew/equipment: When spying on a gun emplacement, LeBeau is dressed as a little old lady. When putting on his shawl before going back, you can see the studio lighting reflected on the glasses he wears.
Anchors Aweigh, Men of Stalag 13 - S1-E16
Visible crew/equipment: When in Klink's office, Hogan gives Klink the bum's rush, convincing him that he's tired. After Klink sits, the camera pans around. As it does so, you can see the shadow of the camera rig.
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