Bob Crane as Col. Robert Hogan, though this is actually coincidental; the character was named after actor Robert Hogan, who was a friend of co-creator Bernard Fein, and director Gene Reynolds.
On occasion, Ivan Dixon as Ivan Kinchloe (even though Kinch's original first name was James).
Fake Nationality: Almost completely averted. John Banner was Austrian, the rest of the cast matched the nationality of their characters. Major Hochstetter — a character not in the main cast — was played by an American actor, as was French resistance leader Tiger.
Averted with Bob Crane and Werner Klemperer; Crane loved playing Hogan and wanted to be remembered as such, while Klemperer mentioned on The Pat Sajak Show that he's perfectly okay with people coming up to him and saying, "Hi, Colonel [Klink]!"
Inverted with Richard Dawson, who spent a number of years trying to form his own identity, separate from Newkirk; in fact, when appearing on The Dinah Shore Show with Caroll Spinney and Oscar the Grouch, Spinney had Oscar ask, "So, Dawson, how's everything over at Hogan's Heroes? Heh-heh-heh!" and Dawson was not amused.
Many of the actors playing Germans on the show were Jews who left Europe to escape the Nazi regime. They took parts in the show because the heroes would always outsmart the Nazis. Leon Askin (who played General Burkhalter) had a prominent scar on his cheek from being beaten in the street because of his religion and this was handwaved away in-universe as a fencing scarnote Many German officers had such scars since it was a sign of bravery because that they didn't flinch as rapiers were being swiped at their faces. Many would sew horsehair into the open wound to make the scar as prominent as possible
Colonel Klink was depicted as an incompetent musician. Werner Klemperer was a highly gifted violinist and came from a long line of musicians.
Money, Dear Boy: Co-creator Albert S. Ruddy wanted nothing to do with the series. When he was offered a position on the show's writing staff, he turned it down to concentrate on writing screenplays for movies; the main reason he co-wrote the pilot episode was at the suggestion of a colleague who said he would be paid rather nicely as the creator of a weekly series, as common practice back in those days was whoever wrote the pilot episode of a series was credited as the creator(s).
Hogan's womanizing took on a new light when the seedy details of Bob Crane's private life came out. Crane also married Sigrid Valdis who played Hilda, the secretary with whom Hogan had an implied relationship.
Carter almost never takes off his gloves. If you look at one of the very rare scenes where he's bare-handed you can see that he's wearing a wedding ring. Larry Hovis, his actor, refused to remove it even while he was acting.
Recycled Set: It's subtle, but if astute viewers pay really close attention, anytime the heroes are doing business in a different barrack, it's clearly the exact same set as Hogan's barrack, with the bunks and lockers and such rearranged. Even the interior of the new Rec Hall in Season Six, the front wall is the same, a bookcase is inserted in the doorway.
Unintentional Period Piece: The producers of the DVDs seem to think so, the show is described as being "timeless" on DVD packages, however, with this show obviously taking place in a German prisoner of war camp in WW2, it's a period piece no matter how you look at it.
In separate interviews, both Werner Klemperer and Richard Dawson have hinted that there was a possible seventh season in production, but was more than likely stopped, due to the series falling victim to The Rural Purge. There has also been some hinting that the supposed seventh season was to be the real last season, including a final episode in which the war ends, the POWs are liberated.
Richard Dawson wanted to give Newkirk a Liverpool accent in order to avoid the stereotype that all British characters speak in a cockney accent. However, people were having a difficult time understanding his dialogue, and he was asked to give Newkirk a cockney accent after all, to which request he relented. Ironically, shortly after the pilot was filmed, A Hard Day's Night was released and went over really well with audiences, leaving Dawson to ponder that if audiences could understand what The Beatles said, surely they could've understood Newkirk.
Co-creator Albert S. Ruddy said that the show was originally set in a modern-day American jail (though the premise of the prisoners carrying on operations under the guard's noses was still intact), but when he got wind of another series being developed for NBC set in an Italian prison camp in WW2, he reworked the series' setting into a German prison camp. In fact, when the other pilot (Campo44) finally made it to air in 1967, it was heavily criticized as being a rip-off of Hogan's Heroes.
Ruddy was also offered to be a staff writer on the series, but turned down the offer, as he didn't even want to be involved with the show's production anyway; he wanted to write movies instead, and only co-wrote the pilot episode to have a series creator credit to his name.
The series has a shared reality with Green Acres. During a flashback from Oliver's World War II years, both Colonel Hogan and Stalag 13 are mentioned. Colonel Klink also showed up in — of all places! — the Batman TV show and The Simpsons.