Happy Days

In the first scene at Arnold's, Henry Winkler originally says, "I'm leaving tonight on the five o'clock bus," but his voice is later dubbed to say, "I'm leaving tonight on the four o'clock bus."

This episode is also known as "Guess Who's Coming for Christmas."

This is Randolph Roberts' last appearance as Chuck although the character is mentioned again later in the season.

When this episode was rerun in 1975 and 1976, there was a newly-shot introduction where Fonzie prefaces the story mentioning that Chuck was home for the holidays in the process. This is the only time that Chuck was referred to in the third and following seasons. It was re-capped/re-run twice with a Pat Morita (Arnold) episode and an Al Molinaro (Al) episode. Some packages sold to international markets show the recapped Al version in place of the original episode.

This episode features the first shot of Fonzie's apartment.