Acting for Two: Cloris Leachman plays both Barbara-June "Maw Maw" Thompson and her 104 year old mother Norma June Thompson in "Mother's Day".
Actor Allusion: In the Episode "A Germ of a Story" when watching home movie from Virginia's childhood, Burt says Maw Maw looks like the neighbor from The Mary Tyler Moore Show - Cloris Leachman's character on that show.
Virginia calls the whipped husband played by Ethan Suplee from the episode "Baby Monitor", "...a skinny version of the dude from Mall Rats." Ethan Suplee did play that character in the movie.
Smokey Floyd returns in "Making The Band" with a list of people he's wronged that he is making amends to, complete with My Name Is Earl theme music, he is joined by the actors who played Randy, Darnell, Joy and Catalina as well as TV's Tim Stack.
In "Yo Zappa Do", Brian Doyle-Murray appears as a president of a movie studio. Of course considering who appear next, it could have been the actual Mr. Savitsky. In the same episode, Virginia points out that child actors never last. They appear in a Steven Spielberg movie and then end up "as the mom on a wacky sitcom."