Factual error: About 8 minutes into show, Major Hochstetter asks Schultz how long Colonel Hogan (an American) has been running the camp, and Schultz says 3 years last November. This is impossible. The US didn't get into the war until December, 1941, He would have to have been captured November '42 or earlier but the war was over by November 1945.
Factual error: Hogan mentions a store that offers "thirty percent off on T-shirts." T-shirts were mostly unknown in Germany during the 3rd Reich, and didn't see widespread use before the 1960s. Before that, the traditional Unterhemd, known in America as tank top or wife beater, was worn almost exclusively.
Factual error: In this episode, the Royal Navy submarine that acts as a radio relay for Hogan's men is hunted by a destroyer. Like in most such Hollywood scenes, depth charges are seen exploding right next to the submarine, which just shrugs the blasts off. In reality, any depth charge that went off closer than 100 meters was instantly deadly to a submerged sub.
Factual error: When the farmer sticks his pitchfork into the haystack, a scream is heard, but then everybody emerges unscathed. Wounds from pitchforks 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: When the three captured heroes stand before the Gestapo officer, he sweeps three sets of US identification tags into his hand. The names and uniforms suggest that the three captured personnel are from three different armies. Identification tags differ greatly between armies, all wearing US-style with their usual uniforms they would be worse off than wearing none at all. The Geneva convention would allow for them to be shot on the spot as spies under these circumstances since they initiated combat (blew something up) wearing false uniforms. (00:03:20)
Factual error: When the men are lined up to take the strongboxes of gold to switch with bricks, each man in line easily hefts and tosses them to the next man. Gold bricks weigh over 27.5 pounds (12.4kg) apiece. If there 10 bricks per box (going by the size of the boxes), then that comes to 275 pounds per box, plus the weight of the box, which these guys are tossing around without a problem.
Factual error: Several times in the series, maps purporting to show Russia have the title "Union of Soviet Socialist Republics" (USSR). This name existed only after the war ended, before that, they were independent countries until they were annexed by the then Soviets.
Factual error: The medal Newkirk steals from the German officer in the pub is a Knight's Cross of the Iron Cross with Oak Leaves and Swords. There were a total of 148 presentations, most of them 1943-45. By 1942 (where the series is apparently set), less than 25 had been presented. That Newkirk should actually stumble across a wearer by pure chance is highly unlikely, that the wearer should actually "never miss it" as Newkirk states, is plainly impossible. Being the fourth highest ranking military decoration of the Wehrmacht, it would have been missed almost immediately - if not by the wearer himself, then by his fellow officers. (00:22:35)