Jack (John Ritter) sings "Jingle, Jangle, Jingle" while pretending to be his cowboy twin. In 1942, John's father, country artist Tex Ritter, recorded this song as one of the first records produced by the new Capitol Records.
In the opening scene, Cindy is wearing the same shirt she'd wear in the intro for the next three seasons.
It's implied that Furley's brother Bart is 48 years old in this episode.