I Look Better in Basic Black - S1-E28
Revealing mistake: A very long fuse is laid down then lit by the boys to distract the guards. While it is burning, watch the fuse in the dirt - it is actually being pulled from offscreen to the right of the shot.
Factual error: In three episodes of season 1, an aircraft is shown dropping parachutists. This aircraft is a Fairchild C-119. First flown as the C-82 Packet on Sep. 10, 1944, it wasn't operational until 1947.
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)
The 43rd, a Moving Story - S1-E23
Other mistake: When Hogan uses the water barrel periscope to spot Manor Kuhn, the first shot is from an impossible angle.
The Late Inspector General - S1-E4
Other mistake: While the General is in Klink's office making the recommendation for Klink to be commandant of all German POW camps, he mistakenly calls Stalag 13, Camp 13 three different times. Camp 13 was referenced in the black and white pilot episode.
Suggested correction: Stalag is short for "Stammlager." "Lager" is the German word for "camp." (To avoid unnecessary discussions: depending on the context, "Lager" can also mean stash, cache, storage, warehouse, bedding or bearing, but in this context it is indubitably to be translated as camp). So "Camp 13" is absolutely correct in this context.
Other mistake: Hogan is disarming a booby trap briefcase. The bomb expert tells him over the radio he has to decide to turn the handle clockwise or counterclockwise. The expert doesn't know which way to turn it. Hogan turns the handle counterclockwise and disarms the booby trap, and the expert says counterclockwise. There's no way the expert would have known which way Hogan turned the handle. (00:21:50 - 00:22:26)
Suggested correction: He didn't know, which is why he asked it as a question. He said "counter-clockwise?"
Suggested correction: Umm probably because he didn't hear a loud explosion.
Factual error: While introducing himself to the downed Russian pilot, Hogan claims he is with the "US Air Force." He was actually with the United States Army Air Corps (USAAC) as the US Air Force wasn't formed until 1947, 2 years after the war ended.
Oil for the Lamps of Hogan - S1-E14
Plot hole: The Heroes take an empty oil drum to the depot, knowing full well that Schulz will protest, allowing them to steal a full one. However, all but their barrel have snow on it. Since it's really salt, it all falls off as they load it on the cart. With real snow, that wouldn't happen. It would be quite obvious that the barrel they are taking out is not the one they brought in.
Plot hole: Five minutes into the show, Klink and Hogan are in Klink's office when a gestapo major comes in. When Hogan leaves, Klink mentions Hogan's name and the major realises with surprise that that is Hogan and then says he knows all about Hogan and his description. That alone should have led the major to know that this was Hogan. Hogan also has his name on a tag on his jacket.
German Bridge Is Falling Down - S1-E7
Continuity mistake: During his experiments to create explosives in the tunnels, Carter has a pretty extensive set of glassware on his workbench. Necessarily he would have to replace (most of) that after each explosion - not to mention various light bulbs, furniture and other non-blast-proof stuff by the way. A lot of that glassware is specialty equipment, it would not be easy to come by even one set of in peacetime for a free civilian. In wartime, for an allied prisoner (even with the heroes' connections) it should be nigh impossible, and totally impossible to have an inexhaustible supply of the stuff. So we can either assume a giant plot hole, or treat it (as I did) as a big continuity mistake.
Suggested correction: Considering they regularly get equipment of all kind air dropped from "London", a few laboratory instruments and containers would hardly be challenge.
Firstly, considering the number of explosions, it's not "a few" but more like "QUITE a few." Secondly, if they had had the option to receive airdrops at the time, they would just as have had them airdrop the explosives instead of the glassware for carter to blow up, wouldn't they? Or are you suggesting they would have more spare laboratory equipment in store than a wholesale laboratory outfitter, "just in case"?
Happy Birthday, Dear Hogan - S4-E26
Continuity mistake: LeBeau meets a female underground contact in a movie theater. They have to kiss to avoid detection by the Gestapo. When LeBeau leaves the theater there are no lip stick kisses on his right cheek, but when he returns to camp he has some. (00:18:00 - 00:19:00)
Suggested correction: Simple, they kissed again before LeBeau arrived back at camp. Nothing to see here.
Lady Chitterly's Lover: Part 1 - S6-E4
Continuity mistake: As the boys look at the falling plane, it's light enough to see their shadows. As the guards rush out, it's suddenly dark.
Never Play Cards with Strangers - S4-E7
Visible crew/equipment: As Hogan takes off with Von Treger's car, the camera crew and equipment are reflected in the windows.
Continuity mistake: As Newkirk says he volunteers, he straightens to attention, hands by his sides. A second later, his hands are in front" holding a bit of laundry.
Hogan and the Lady Doctor - S2-E20
Other mistake: As Hogan and company listen to Klink's office, the lid is on the speaker, so they shouldn't have been heard or at all.
Praise the Fuhrer and Pass the Ammunition - S2-E19
Continuity mistake: As Klink tells Hogan of his suspicion, his arms are folded. A second later, his left fist is by his mouth.
Plot hole: Hogan's men have that clever device in Klink's quarters, where they turn the oven from below to reveal the trap door. That however unplugs the oven from the chimney, you can even see the smoke pouring out of the oven in some shots. Often enough, they have the oven unplugged for half a minute or more. If an oven smoked into a room that long, the whole room would fill with smoke so badly it could actually lead to smoke poisoning. If nothing else, Klink would have the oven checked. Any device that can turn a heavy cast-iron stove flawlessly like that would by definition have to be quite massive and not disassemble easily. If Klink had the oven checked, that would certainly lead to the discovery of the turning mechanism.
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.
Continuity mistake: In this episode, the picture next to the light switch wire is a group seated around a table. In "The Defector" (S5:Ep10) the picture was of Hitler making a speech, and the microphone he's speaking into hides the Heroes' bug.