Anachronisms: In one scene taking place in a German laboratory, a periodic table of elements is hanging on a wall. It shows all the 103 elements known to science in the 1960s, but during the war, fewer than 92 elements were known: the rest were created by nuclear science, including several instrumental in the top-secret Manhattan Project.
Continuity: In numerous episodes, when it is supposedly winter with patches of snow on the ground, you can see leaves still on the trees in the background.
Factual errors: There are no colonels in the Royal Air Force. The equivalent ranks are Wing Commander for a Lieutenant Colonel, or Group Captain for full Colonel. "Colonel" Crittenden who is supposed to be, and wears the insignia, of equal rank to Hogan, should have actually been Group Captain Crittenden.
Continuity: In the episode with the gold bricks which Hogan and the gang make into steps, the following episodes have the steps back as wooden ones again.
Revealing mistakes: Sometimes you see the warning "Gebrauch keine Haken" on boxes in the background. This is a literal translation of the English "Do not use hooks" and would never be written in that form on a German box. Correctly it would have to be "Keine Haken verwenden".
Factual errors: The Gestapo did not wear black uniforms as seen in Hogan's Heroes. While it was certainly a nice touch of artistic license to differentiate the more sinister Gestapo like Major Hochstetter from the relatively benign Luftwaffe guards, this type of black uniform was a ceremonial uniform seen mostly on the guards at important buildings or at state functions. The appearances by the Gestapo in plain clothes and a Nazi party tie pin are closer to the truth.
Miscellaneous: Carter usually wore gloves, but many times he didn't, and a wedding ring is visible.
Factual errors: The Germans usually address each other by the U.S. equivalent of their ranks. Sergeant Schultz's rank is "Oberfeldwebel". Colonel Klink is "Oberst". Captain Gruber is "Hauptmann". The Gestapo and S.S. had their own rank system, which was different than the traditional military rank system, so Major Hochstetter should not be called 'Major'.
Factual errors: Major Hochstetter's collar insignia is that of a Standatenführer or the U.S. Army equivalent is a full colonel.
Factual errors: The center top ribbon on Colonel Hogan's dress uniform is the Air Force Distinguished Service Medal, an award that was created by the Air Force after World War II.
Factual errors: Hogan and the other Heroes would never have been stationed together. There was a separate POW camp for officers.
Continuity: In "The Scientist", Carter states that he can't teach LeBeau any chemistry because he ran a drugstore, not a chemist's shop. But in the earlier episode "German Bridge Is Falling Down", he knew how to make explosive chlorine gas out of ammonia and bleach, and in the later episode "Hogan Springs", he mixed up a convincing batch of "mineral water" with no difficulty.
Anachronisms: Although the series takes place during World War II, the women wear the clothing and hairstyles of the 1960's.
Anachronisms: Hogan often identifies himself as a member of the United States Air Force. However, he should have said U.S. Army Air Corps as the Air Force did not become a separate branch until 1947.
Factual errors: In several episodes, as Sergeant Schultz is patrolling, it is very apparent that the rifle he carries is a Krag-Jorgensen rifle, of Norwegian origin (the type was also standard issue in the US military prior to the adoption of the Springfield M1903). While non-standard equipment did find its way into the German military, the series is depicted to occur prior to the Allied landings in Normandy - a time when the issuance of such non-standard equipment would be highly unlikely. The standard issue rifle for German forces of the time was the Karabiner 98 Mauser.
Continuity: During the first season, the name of POW camp keeps alternating between Stalag 13 and Camp 13 for no apparent reason.