In his first Arnold's scene, Fonzie says "I'm leaving tonight on the five o'clock bus," but his voice is dubbed to say "four" instead of "five."
This episode is also known as "Guess Who's Coming For Christmas."
This is Randolph Roberts' last appearance as Chuck. The character is mentioned again later in the season.
This episode was rerun in 1975 and 1976 with a new introduction where Fonzie prefaces the story, mentioning that Chuck was home for the holidays. This is the character's only reference in the third/fourth seasons.
Richie: (referring to Fonzie) He was alone in the garage eating ravioli out of a can. Now, what kind of a way is that to spend Christmas Eve?
Marion: What would we do without you, Fonzie?
Fonzie: Well, you'd be up a creek, Mrs. C.
Richie: Yeah, our car'd be stuck in the snow, our tree'd be out, and our Santa Claus would be mugging the neighbors.
Howard: We're gonna have fun. Look, we'll, we'll pop popcorn, and we'll toast the marshmallows, and we'll drink some cider and trim the tree, and then, later on, I'll read The Night Before Christmas.
Joanie: (singing) Jingle bells, jingle bells, boring all the way...
Howard: No singing at the table, Joanie.