An early episode refers to him possessing the willpower to avoid alcohol, which suggests that he was once an alcoholic.

This episode refers back to the Peru mission as there is mention of him being de-briefed about it.

The first episode refers to these as one textbook, two workbooks and audiocassettes.

Several episodes refer to him as a former rebel and troublemaker, much like his sons.

Otherwise, the episode refers to other TV shows.

In addition, episodes written by Darin Morgan often referred to other films.

Later episodes were largely self-contained, albeit referring to previous events and with additional character development.

The episode refers to the long-running joke of Springfield's unknown and unidentifiable location.

Songs mark episodes in the action from records from their collection-the title refers to a song of the same name.

The episode refers to it as "a Festivus for the rest of us", referencing its non-commercial aspect.