That color episode you saw was the only color show of the first 2 years of Hazel. It was done to show off color to the then new Color TV buyers. This show was from 1960 or '61 before all TV turned color but it was bound to come and this episode concerned buying a color TV and so the show was also in color. NBC turned into color first and that's also why Hazel went color before other shows did from the same time period on different networks. If you'll notice carefully, the opening while similar to the b/w round the kitchen table opening is slightly different, Harold doesn't skip backward and Mr. B. keeps his hand hidden since it was broken at the time of the color film opening shoot.