Other mistake: As LeBeau is being interrogated, on the barometer behind Schultz you can make out the word "fair." What is a barometer labeled in English doing in a German counter-intelligence headquarters?
Never Play Cards with Strangers - S4-E7
Other mistake: As Carter brings the German truck to a rough stop, in the closeup, you can see that although Carter and Newkirk lurch in the seats, the truck was already motionless.
Other mistake: In the tunnel where the prisoners are storing ammunition. Col Hogan tells his men the next one that lights a cigarette gets a court martial. The tunnel is lit by open flames. (00:06:00)
Man's Best Friend Is Not His Dog - S4-E6
Other mistake: When seeing the tanks through the viewfinder, Carter's hands and the background are frozen, and the tanks are actually a clip of a wartime newsreel.
Other mistake: Carter said the plans and note were in the box that was supposed to contain a model of the Hindenburg. However, the box he's building out of has "STUKA" on the side.
Color the Luftwaffe Red - S4-E8
Other mistake: The telephone booth located by the Luftwaffe HQ appears to be one of the London police boxes.
Man's Best Friend Is Not His Dog - S4-E6
Other mistake: When referring to the barracks, usually Klink will refer to the buildings by their numbers (Barracks 2, barracks 3, etc.). In this episode, he calls the building "Building G".
Happy Birthday, Dear Hogan - S4-E26
Other mistake: Hogan returns to camp after meeting with the underground, after learning the Germans are setting a trap. Kinch went down in the tunnel to Radio London just before Hogan returned. Hogan asked the men, "Where's Kinch?" and he shouldn't send any messages. Since Kinch was in the tunnel, Hogan should have seen or heard Kinch in the tunnel using the radio. (00:07:50 - 00:10:45)
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