Margaret Hamilton (Wicked Witch of the West) is the second cast member from The Wizard of Oz (1939) to be a guest star. The first one was Ray Bolger (The Scarecrow). The funny part is they both playing a parent of one of the main characters. Ray Bolger played Shirley's dad and Margaret Hamilton played Rueben's mom Clara.
Not sure if this was intentional or not, but Reuben's mother's nickname for him was "Ruby".... coincidentally the same color of the slippers Margaret Hamilton's character was after in The Wizard of Oz.
Reuben's full name is Reuben Clarence Kincaid.