Revealing mistake: At the end, when the boys are in formation and Klink is walking through the ranks, he walks around Hogan's right side. As he does so, you can see LA's Desilu water tower.
Revealing mistake: When the High Command men are watching the "noiseless engine" plane, the camera cuts to a shot of the four of them in the car. To the right (camera's left) of the man in the right side, back seat, you can see LA's Desilu water tower.
Top Hat, White Tie and Bomb Sights - S1-E10
Other mistake: When Klink is trying to demonstrate the automated gates to Burkhalter, Kinch makes the gates close, knocking Klink into Burkhalter. Before Klink tells Schultz to open the gates, they are already in motion.
Go Light on the Heavy Water - S1-E9
Continuity mistake: When the smoke bomb goes off, Klink has his monocle on. After the smoke really starts, his monocle is gone without being taken off.
Go Light on the Heavy Water - S1-E9
Other mistake: After the smoke bomb goes off in Klink's office, there is a shot from the outside where the boys get a blanket to catch Klink. If you look at the window of the office behind them, you can see the smoke coming out in an up and down pattern, suggesting the smoke to be coming from a rig controlled by an out-of-sight crew member.
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.
Continuity mistake: The boxes being carried into the buildings in the beginning of the episode were about sixteen inches high by three feet long. When the bomber plane is dropping bombs, what drops out is a lot bigger than the dimensions of the boxes.
Revealing mistake: While talking about Von Baler's daughter, Hogan is facing the building talking with Carter and Newkirk. Behind him is an open area of the camp. If you look, you can see that there is no guard in The Tower, no shadow of The Tower of the guard hut (the sun is behind them and Hogan), and the snow is piled up about three feet behind Hogan, suggesting that the background is a wall mural in the studio.
Clearance Sale at the Black Market - S4-E1
Revealing mistake: The Major goes to shoot out the light that the boys have turned on so Kinch can get the pictures. The first shot is angled too low to hit the bulb, but there is no impact on the front of the door's crosspiece; the smoke and dust comes from behind it. The second shot gets the bulb, but there is no muzzle flash, just sound. Also, there is no impact mark on the brick wall behind the bulb.
Clearance Sale at the Black Market - S4-E1
Continuity mistake: When Hogan is talking to Kiegel, Hogan's eyes are level as he looks across the table at Kiegel. After Kiegel says "Not good enough!", the camera cuts to a close up of Hogan, and he's now looking up as if the Major is standing. A moment later, the Major stands and leaves.
Other mistake: After the truck is stopped, Newkirk tosses a dart at the tyre in order to flatten it. Since the tyre hit was the rear tire, there should have been the track from the front tire, but wasn't. Also, a puny, hand-tossed dart couldn't have penetrated the thick construction of a heavy-duty truck tire, let alone flatten it in twenty seconds.
Other mistake: When stopping the truck and Schultz, the area directly behind Carter and LeBeau can be seen to be a matte painting. The reason is because where they are is completely covered in snow, but the open area is very little, and there is a huge snowdrift piled up at the wall.
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.
Other mistake: When the boys are working on the "jigsaw" map, Klink and the guard come in. There is a gust of wind from their entrance. Trouble is, the gust that blows the pieces comes from behind LeBeau, blowing the pieces toward Newkirk's bunk, rather than toward the camera.
Continuity mistake: Klink comes out with the "insurance policies" in his hand. They are lying beside each other, with a little space between them, and tilted in one position in his hand. When the camera goes into a close up, they are touching, and in a different position.
Continuity mistake: When the woman is kissing Klink in town, she hands a note to the boy who puts the note inside the spare tire's hubcap. There was no tape to stick it anywhere, yet when LeBeau goes to get the note, it is stuck with tape to the center of the spare tire.
Audio problem: When Klink comes into the barracks, he puts the bottle of alcohol into his jacket to hide it. When he does, you hear a distinct clink (no pun intended) of glass on metal. None of the POWs wear anything that would cause this.
Continuity mistake: After Hogan calls off the volleyball game to go see what Kinch wants, he goes into the barracks. From the outside, the door is already open. When the camera shot is indoors, Hogan is opening the door again.
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