Two Nazis for the Price of One - S3-E17
Corrected entry: When Hogan is bending the antennae into a swastika, there are no extra pieces; all the bends are smooth. When it's on the flagpole/antennae, there is a short, extra piece under it to attach it to the mast.
Reservations Are Required - S1-E15
Corrected entry: When LeBeau goes to get out under the wire, he raises an entire section of the wire on the inner and outer fences to do so. It can be seen that there is a bar on the bottom of the sections that he raises that suggests the sections are totally framed for the purpose.
German Bridge Is Falling Down - S1-E7
Corrected entry: In the very beginning, the prisoners are all in formation for a count. Shultz completes the count at 15, reports it, and Klink calls Hogan over to talk. This leaves 14 in formation. Hogan says "Smoke if you have them". Unbeknownst to Klink, the men are in an arrow formation to point the way to the bridge for the bombers. The aerial shot from the planes shows at least 25 lighters lit. Where did the other 11 guys come from? With Hogan, his barracks only had 15 men who would've been in on it.
Correction: First, it's not true that only the men from Hogan's barracks are in on their operations. It's mentioned in several episodes that they've used other men during their missions. During S1E22 Hogan sends his people out to find a pizza recipe which is hardly the most inconspicuous thing to ask in a POW camp. During S1E27 Hogan asks Kinch if there's a Safe cracker among the prisoners in the camp, so he obviously has no problem recruiting people from outside his barracks. Second, the moment Hogan steps towards Klink, the prisoners break ranks and start to mingle. We simply have to assume that not only Hogan's barracks were ordered to fall out, but other barracks as well, (which would only be logical) even though it happens out of frame. The reason is obvious as well - it's hardly news that the producers of Hogan's Heroes were kept on a pretty tight leash budget-wise. Last but not least, it's true that Schultz counts to 15, but if you count yourself, you will find that not 15 but 19 people are in formation in front of the barracks in the first place. In conclusion, there is a valid mistake right there, but it's not the fact that the arrow consists of more than 15 people.
I stand corrected.
The Informer - S1-E1
Corrected entry: In this episode, the German spy Hogan conducts around the Underground tunnels sees things (i.e., steam room, weapon manufacturing line, barber shop, etc.) that are never seen in the series again.
Correction: It is never made quite clear whether those were really supposed to be a thing or just part of an extremely elaborate plot to throw off the spy. Admittedly, if they were supposed to be part of the plot, the question how Hogan's men managed to set up such a complicated system in the time available would be a mistake in its own right.
Corrected entry: On the cover of the plan for Operation Hannibal, the top line says. "SEHR GEHEIM" (Top Secret). But the plan is called Operation Hannibal (translated as "betrieb hannibal"). The title says "unternehmen hannibal (translation: Companies Hannibal).
Corrected entry: The whole story line is a plot hole. The blueprints would be a top secret item, and as such, wouldn't accompany the item they depict (in this case, missiles). Klink carries the prints around as if they were ordinary papers for no other purpose than to be "borrowed", copied, and returned by the Heroes. For this, Klink would have been eliminated.
Correction: Not a plot hole. The rationale for the plans being present was probably because they were to be presented to the assembled general staff. That makes it a deus ex, not a mistake. It's often stated in the series how the Axis general staff considers Stalag 13 a particularly safe place, so there's no reason not to take top secret plans there. As a matter of fact, the safety is precisely the reason the demonstration is held in Stalag 13. As for the reason Klink carries the plans with him, that's not a proper plot hole either. Again, viewed from the German point of view, the plans were safe there, especially rolled up where nobody could peek at them. After all, no prisoner had ever escaped from Stalag 13. Fact is, the Germans have no clue that Hogan's men have ways to get those plans out of country. True, Klink probably shouldn't have put the plans down, but that's just his usual clumsy self, and as already pointed out twice, from his point of view he had no reason to suspect duplicity.
Corrected entry: When Major Hagel is going down the list of his knowledge of Hogan's Heroes, he mentions that their code name is Goldilocks. Throughout the series, the code was also Mama Bear, but the most used code name was Papa Bear.
Correction: The Heroes used all of these codenames. Papa Bear is the codename of Hogan himself, Goldilocks is the codename of the whole team around Hogan, and Mama Bear is the codename of the U-Boat they're in contact with.
Corrected entry: As the scene fades to the Höf Brau (with lighting that would violate black out rules in wartime Germany) passing vehicles can be seen to be modern (mid-1960's) cars rather than the more appropriate early 1940's German vehicles. And they're travelling at 1960's standards speeds.
Correction: Only the headlights of the cars are visible for less than a second, plus, the reporter presumes to accurately judge speeds of cars in a movie scene, which would be difficult at best. Furthermore the mistake depends on the assumption that speeds were significantly different inside closed settlements between 1940 and 1960, which they were not. Legally, in Germany, 40 km/h would be permissible in 1942 whereas 50km/h would be permissible in 1960. In California, the speed limit would have been between 25 and 30 mph, or 40-48 km/h respectively. Even in real life, accurately judging a speed difference of 8km/h would be almost impossible except in direct comparison. This mistake should probably be upheld in part, but either it must be rewritten without the speed stuff, or a comprehensible explanation must be given how the difference in speed is to be explained and judged.
Request Permission to Escape - S1-E32
Corrected entry: As Schultz goes to salute, the water stream goes up Klink's face to shoot over his head. When the camera cuts to Schultz, the stream now is aimed more directly at Klink's face.
Funny Thing Happened on the Way to London - S3-E5
Corrected entry: When Hogan goes to shake hands with Baumann, he grabs and raises Baumann's arm to make the wrist gun fire upwards. As it fires, it takes Klink's hat off. Upon inspection, Klink's hat has only one hole, as if fired through from underneath. The gun fired at the peak of the hat, therefore, there should be a second hole about the level of the top of the eagle on the front of the hat.
The Late Inspector General - S1-E4
Corrected entry: When the Inspector General walks toward Klink's office, he falls into a fake tunnel section. As he goes down, he has his outer coat over his shoulders. When the shot cuts to him in the hole, the coat is missing without having fallen off. After he is out, the coat is returned.
Correction: Not a mistake. The coat does fall off his shoulders and one of the staff members starts to get it... Watch closely.
Corrected entry: 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.
Correction: The USSR was created in 1922, two decades before World War 2.
Correction: That is not a continuity mistake. The extra piece would have been affixed (glued) to the large swastika antenna before mounting, not when Hogan bent the poles into shape. Just because it wasn't shown as added does not make it a continuity mistake. It was added off camera and in another time frame.