Factual error: Throughout the show, German officers talk about "Nazi" this, "Nazi" that, even in official capacity. In fact, the mere mention of the diminutive "Nazi" could get you in serious hot water for the disrespect and dissent it implied. Correct would be either "National Socialist" or some reference to the Reich: e.g. "Officer of the Third Reich" instead of "Nazi officer."
Factual error: In this episode, the running gag is that Schultz keeps flattening Col. Hogan's pumpernickel loaves. In reality, pumpernickel is a very compact bread that contains virtually no air at all and is impossible to flatten in this way. The shape is also wrong: pumpernickel is almost always baked in rectangular baking pans.
Factual error: When the crew in the plane gets ready to drop the bombs on the refinery, Hogan (in the pilot seat) tells Carter (who is looking through the bomb sight) exactly when to push the button. In fact, the pilot of a WW2 bomber had no way of even knowing when exactly to release the bombs - it was the job of the bombardier, looking through his targeting optics, to know that. Carter at the bomb sight should be telling Hogan how exactly to steer to get the bombs onto the target.
Factual error: The "Blue Baron" tells the dancer that the Kaiser gave him a certain medal. In fact, the medal he points to (and the girl fondles) is a WW2 repeat badge to the Iron Cross first class, instituted in 1939 to denote presentations of the Iron Cross first class to personnel who had already received it in WW1. He may have received the original Iron Cross from the Kaiser, but by the time he had a chance to receive that repeat badge, the Kaiser was long through handing out medals.
Factual error: When the farmer sticks his turning fork into the haystack, a scream is heard, but then everybody emerges unscathed. Wounds from turning forks aren't like sitting on a brass tack - even a quick jab usually earns you a trip to the surgeon (I've seen such wounds), a vigorous stab like the one in the scene would go through limbs and could easily kill a man. There's no way anybody would walk away from such a hit.
Factual error: Klink usually wears an EK1 (EK= Eisernes Kreuz = Iron Cross first/second class) chest cross with a WW1 EK1 repeat badge, but he neither wears an EK2 ribbon nor a WW1 EK2 repeat badge. This is not a legal combination, he either has to wear both or none at all. The EK1 and EK2 repeat badges were awarded to soldiers who were awarded an EK1 in WW1 and another in WW2. To be awarded an EK1, you had to have the EK2 already. The Legal combinations would be: EK2 ribbon in the button hole with or without EK1 chest cross, EK2 ribbon in the button hole with repeat badge with or without EK1 chest cross, again with or without repeat badge. One legal way of wearing it is seen in S5E3, "The Klink Commandos", where Hogan wears a black-and-white WW1 EK2 ribbon with repeat badge and an EK1 chest cross with repeat badge. It doesn't make any sense for him to wear that (separate mistake), but the way of wearing it is correct.
Factual error: During the show, many (not to say most) higher officers are seen wearing a Knight's Cross with Crossed Swords and Oak Leaves, the fourth highest award for military valor of the Third Reich. In fact, a total of 177 of this and higher-ranking medals were awarded during the entire war, most of them in '43 and after. The series is allegedly set mostly in '42. Historically correct, most Knight's crosses should be of base rank or with oak leaves only, as of these categories more than 8000 were presented.
Factual error: In many episodes, SS members of all ranks appear - the most notorious recurring character being Major Hochstetter. Curiously enough, Hochstetter couldn't have been a Major in the SS, simply because that rank didn't exist there. The SS used the SA rank system, not the Wehrmacht one. Hochstetter for example would have to be a Sturmbannführer. Colonel Feldkamp would have to be a Standartenführer.
Factual error: General Kamler awards Schultz what he calls "The Iron Cross Fourth Grade." There never was a version of the Iron cross called that. The Iron cross came in two ranks, called 2nd class ("zweiter Klasse") and 1st class ("erster Klasse"). The ranks higher than that were called the Knight's Cross ("Ritterkreuz des Eisernen Kreuzes") and were never pinned to the chest but worn around the neck.
Factual error: All through this episode, characters keep referring to the river the bridge *du jour* spans as "The Düsseldorf" or "Düsseldorf river." The city of Düsseldorf is situated on the river Rhine - there is no "Düsseldorf river." It's a well known fact that the producers were hardly geography whizzes, but not knowing the Rhine is bad even by their standards.
Factual error: Newkirk deflates a tire by throwing a dart at it. Most of the time, a small-caliber gunshot can't instantly deflate a tire while standing still (SWAT use 12-gauge slugs to do it safely). A dart wouldn't even penetrate the tire wall, let alone deflate it instantly.
Factual error: Klink and Hogan sit behind each other in the P-51 they try to steal. The P-51 is a single-seat airplane, the only twin-seat P-51 are trainers. A trainer would not be at the flight line with the regular airplanes, and if a trainer would actually scramble with the others, it would at least arouse suspicion.
Factual error: In several episodes, Hogan and his men are confronted with mobile missile launchers. These are depicted as a missile on a flatbed from which it is launched at the push of a button. While there existed mobile German missile launchers for the A4 missile better known as "V2", they consisted of a whole column of trucks, among them a transport truck for the missile with erector hydraulics, at least two tankers for the fuel, a control vehicle and several other trucks full of equipment, not counting the transport capability for a dozen or more operators that were necessary to launch them. Also the missiles weren't launched from the transport vehicles, but placed on mobile launch racks that were transported separately.
Factual error: While the barracks were reasonable replicas of the real POW barracks, there was one main difference. The original buildings were elevated to ensure any escape attempts could be stopped. In this series, the barracks are flush on the ground, which makes the tunnel access possible and easy.
Factual error: Burkhalter refers to Jesse Owens winning the gold medals in the Berlin Olympics, and that Hitler left the stadium every time Owens was to be presented a medal. Truth was, Hitler left the stadium when another black man won the day before, and didn't snub Owens at all. In fact, Hitler wasn't in attendance the days Owens won.