Revealing mistake: When the boys are working on the fence, when the camera is on Hogan, you can see a modern metal building in the distance.
A Klink, a Bomb and a Short Fuse - S2-E8
Continuity mistake: The lapels of Schultz's jacket have yellow rectangles where the insignia of rank are. Normally, he has four eagles on them meaning senior Sergeant. In the close ups close to the end, the top piece is missing on the right lapel.
A Klink, a Bomb and a Short Fuse - S2-E8
Other mistake: After Burkhalter gives Klink the order to help disarm the bomb, the camera cuts to Hogan and Klink. Between them and over the barracks, you can see the Desilu water tower.
Heil Klink - S2-E22
Continuity mistake: As Brauner, dressed as Shultz, gets into the staff car, he has no glasses on, as Shultz does not routinely wear them. After the shot cuts to Shultz and back to Brauner, and as the car pulls away, you see Brauner with horn rimmed glasses suddenly on.
The Battle of Stalag 13 - S2-E5
Continuity mistake: At the end, as the staff car leaves, the guard has the gate open. You see it's a single gate, suggesting the fence is a single, whereas in other episodes, you see two sets of wire. The gates are double, with a bar on the top to open both gates (inside and outside) at once.
Other mistake: Hogan is listening to Klink's office with the coffee pot, and the clear top is still on the basket that is the speaker, but you can hear Klink.
Don't Forget to Write - S2-E13
Other mistake: When the recruiting officer is talking to Klink, Hogan and company listen in, as usual. The problem is the coffee pot. Any other time, they take off the top, take out the basket (which is the speaker) and plug in the power: this time, they forgot to remove the top to hear it, which would have muffled the sound. But the conversation was heard just the same.
Praise the Fuhrer and Pass the Ammunition - S2-E19
Continuity mistake: When the German officer throws the dummy grenade, it lands about 15 or so feet from Hogan. In the next shot, Hogan takes only a step or two (about three or four feet) and picks it up.
Hogan and the Lady Doctor - S2-E20
Other mistake: As Hogan and company listen to Klink's office, the lid is on the speaker, so they shouldn't have been heard or at all.
Praise the Fuhrer and Pass the Ammunition - S2-E19
Continuity mistake: As Klink tells Hogan of his suspicion, his arms are folded. A second later, his left fist is by his mouth.
Continuity mistake: When Kinch raises the binoculars to look at The Tower, the neck strap is crossed in an "X" on his chest. When he puts them down, the strap is straightened.
The Battle of Stalag 13 - S2-E5
Continuity mistake: As Hogan leaves Klink to go to his barracks, there is a distinct lighting difference on the porch where Klink is. The area between the supports of the porch roof is lighter in color than to Klink's left, also the shadows of the trusses are at a different slant than the area to the right of the screen. And there are extra shadows of the light and the support to Klink's left.
Everyone Has a Brother-in-Law - S2-E23
Continuity mistake: Hogan is reading the note from the underground on the clipboard that Newkirk brought in. When done reading, Hogan is holding the board at waist height. In the close up, it's suddenly chest height.
Heil Klink - S2-E22
Continuity mistake: The light switch for Klink's office is usually located right next to the door, with the wires going up toward the ceiling. This time, the switch is missing.
Factual error: In the very end, Klink comes up to the boys. As he stands beside Hogan, the Desilu Studios Water Tower is present behind them.
A Klink, a Bomb and a Short Fuse - S2-E8
Continuity mistake: When Burkhalter is standing with Klink after he first arrives, Burkhalter's arms are by his side. When the camera cuts to a close-up, Burkhalter's arms are crossed behind his back, much too quickly than is possible.
Other mistake: When the General arrives at Camp 13 and is greeted by Klink, he notices Hogan and ask Klink who he is. Klink only says he's the Senior POW, the General sends his Aide to get Hogan. The Aide addresses Hogan by name, but Klink never said Hogan's name. (00:07:40)
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