This episode was held over from season three. It was filmed on April 3, 1964. That explains the old living room furniture. Beginning with season four, the Petrie's have a new couch.
Maurice "Buddy" Sorrell mentions that he had written comedy material for Milton Berle three years prior to this episode. He would have had to have special permission from boss Alan Brady to do so. In the 2nd season episode, "The Secret Life of Buddy and Sally", Rob states that Buddy, Sally and he himself all have exclusive contracts to write only for "The Alan Brady Show". (All three have written for Alan Brady longer than Richie Petrie has been alive. Richie would have been about 6 years old when Buddy wrote for Berle.)