Only one episode of Hogan's Heroes was ever shot in black-and-white: the pilot episode. Here is the introduction. You'll note a few changes from the later introductions. The pilot episode had a Russian character in it and Sergeant Carter was absent. Once the series began in earnest, the Russian character was ditched and replaced by Larry Hovis' Sgt. Carter. (Hovis had appeared in the pilot episode as a guest character.) This move actually better reflected reality. Russians captured by the Germans were not treated nearly as well as those from other Allied countries. There would have been no Russians in a Luftstalag.