Mama Carlson says that in her youth she was on Broadway, and then entertains the staff with a song. Carol Bruce actually appeared on Broadway, most notably in two productions of "Showboat".
This is one of the few episodes to give any background information on Arthur Carlson's father Hank.
A textbook example of a "bottle episode," in which the action takes place entirely on pre-existing sets, as if the characters are stuck like "a ship in a bottle." (This is done both to save money and to give the production crew some time off) In this episode, there is literally a liquor bottle passed around among the characters.