Anchors Aweigh, Men of Stalag 13 - S1-E16
Continuity mistake: In Klink's office, as Hogan tries to make a fast exit, Klink calls him back with "I'm not finished with you yet." As he does, his hands are clasped in front of him, then a second later, they are down on the desk.
Continuity mistake: The emblem on the left side of Schultz's helmet is mostly gone. Later when apprehending Stoffel, the emblem is complete.
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.
The Flight of the Valkyrie - S1-E5
Other mistake: As Crittendon pops through the wall, it is easily seen that the wall is Styrofoam, or other similar easily moldable material.
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
Continuity mistake: The ground is soft, dark gray dirt. From the next episode on it is hard packed yellowish clay.
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.
German Bridge Is Falling Down - S1-E7
Continuity mistake: As Klink is talking to the sentry post, his hand goes from around the microphone part to along the length of the receiver between angles.
The Safecracker Suite - S1-E27
Continuity mistake: While Klink is talking to Hogan and the Major, the chair next to the door is almost centered under a picture frame. When the Major is arrested the chair is moved to the left. When Klink sits down, the chair is centered again. (00:03:50)
Kommandant of the Year - S1-E3
Continuity mistake: The missile sitting on the trailer is thin and yellow, the missile actually seen flying is a fat, pointy, silver Atlas missile - which is an American intercontinental missile by the way, not a German tactical missile.
Reservations Are Required - S1-E15
Character mistake: In this episode, Hogan suggests a helicopter as means for escape from Stalag 13. As a matter of fact, the allies had no helicopters operational before April 1944. The famous R-4 made its first flight only in January 1942. So unless Hogan planned to steal one of the Luftwaffe's 20 FW Drache (a maximum of ten or so existing at any given time) or a whole bunch of the single-seat Flettner Kolibri (24 total built) he was out of luck.
Anchors Aweigh, Men of Stalag 13 - S1-E16
Character mistake: Klink claims that the North Sea is about sixty miles from Stalag 13, in reality however the town of Hammelburg and thus the nearby camp are about three-hundred miles from the North Sea.
The Flame Grows Higher - S1-E31
Continuity mistake: At the end, as Schultz and Hogan come out of the office, there is a blank wall, like a kind of foyer. Any shots of the front door from the inside show the door opens directly into the outer office of the secretary.
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)
Anchors Aweigh, Men of Stalag 13 - S1-E16
Continuity mistake: As Klink comes out to see the Officer's club, you can see Hogan is on the ground, and Kinchloe is on the boat by the shade. After a quick close up on Hogan, Hogan's suddenly on board, and Kinch has disappeared in a second.
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.
Go Light on the Heavy Water - S1-E9
Continuity mistake: The boys are looking out the window at the mysterious truck. When the camera looks at them from behind, there's a building right in front of them.
Movies Are Your Best Escape - S1-E8
Continuity mistake: Hogan takes the movie camera from Klink right side up. The next second, it's upside down. Then when Hogan goes to dunk the camera in the water, the lenses are pointing to his right. In the close up, they're facing his left.
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.
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