I think David is treating himself to milk AND pie because he's so pleased with how cleverly he has managed to dispose of Vicki.
For the first time, Elizabeth is wearing that awful yellow hostess gown that will figure so prominently--and in color, no less--in HoDS. Her hair looks great, though. When she worries about David and Vicki, Carolyn tells her not to get one of her premonitions--this is the first and last we hear that Elizabeth has them!
Elizabeth reminisces about the parties at Collinwood when she was young--presumably they were hosted by [spoiler]her father, Jamison[/spoiler]. No doubt he enjoyed the treasure hunts in all the rooms of the West Wing before the rooms were closed off fifty years ago. [spoiler]I never thought about it before, but maybe he closed them off as a cost-saving measure--maybe after the crash of 1929?[/spoiler]
Speaking of fifty years ago, David entertains Vicki with a story of a girl who was trapped in the West Wing and not found for fifty years. He gloats, By then she was dead bones!