The character Nurse Nora Taylor, played by actress Kaiulani Lee, originally appeared in season 4, episode 13, "The Nurse", played then by actress Barbara Eda-Young.
Oddly enough, John Walton reminisces about events in Mary Ellen's childhood that he was not around to witness. The first one is from The Homecoming: A Christmas Story (1971), when he was away from home and the second one is from An Easter Story (1973), when Mary Ellen and GW had gone off by themselves to practice dancing.
First time in the series that the outside kitchen door was seen to function. According to Judy Norton Taylor, behind that door was a functional kitchen for the catering crew.