Factual error: The ambulance Major Teppel transports the prisoners in is a Dodge WC54, which is an American military ambulance, not a German one.
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?
Factual error: Hogan and his men are in Berlin to capture a traitor. They arrive at the Hotel Berlin in an ambulance and park near a K2 phone booth, something only found in England and its colonies, certainly never in the heart of Nazi Germany. (00:13:55)
Continuity mistake: As Major Tepple (Morrison) lays the deck of cards in Hogan's room on the table, the bottom card is not neatly in the deck. When the camera cuts to another angle, the deck is neatly stacked.
Continuity mistake: As the ambulance leaves the hotel, there is snow on top of the fenders and spare tire. Back at the truck, there is snow on the fenders, but not the spare. This would be impossible as at the speed driven, the snow would have blown off any horizontal surface.
Continuity mistake: As Hogan, Carter, and Newkirk go to get out of the Army truck, the ambulance doors are wide open. As Hogan walks by, the doors are straight out toward the truck.
Continuity mistake: In the lobby, Morrison has his gloves on, and never removes them. When he reacts to the gun shot, the gloves are gone.
Continuity mistake: Metsker never removes his right glove, as it is visible in all close ups. In the last wide shot, his glove is suddenly in his left hand.
Continuity mistake: The trick ring Morrison has is on his right hand at the hotel, missing in front of the hotel, and reappears in front of German HQ.
Continuity mistake: When a German Major is in Col Hogan's quarters he is wearing black leather gloves. He raises his hand to remove his hat (with gloves). Next scene he is lowering his hat with bare hands. (00:02:10)
Character mistake: After Le Beau is questioned, Schultz is told to take him back to his cell. Schultz calls "About face! Forward march!" The "about face" is wrong. The door that Le Beau goes out is on his right, therefore the command should have been "right face."
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. (As another contributor previously posted, the term "nimrod" is slang for a nerdy, doofus type of person, though it's unclear why that was his code name).
raywest ★