Castiel says his vessel was ripped apart on a subatomic level by an Archangel. This could either refer to Raphael who vaporized Castiel at the end season 4, or Lucifer who did the same at the end of season 5.
When Castiel urges Claire to eat more vegetables, she replies that ketchup is a vegetable. This is referring to the controversy early in the Reagan administration over school lunch regulations that allowed items such as ketchup to count as a serving of vegetables for meeting nutritional requirements.
Dustin works at Wiener Hut. This is the same restaurant as Alfie, the vessel of the angel Samandriel, from season 8.
Rowena tells Trish that tugging on the chains won't work and Trish replies, "I didn't ask you, Braveheart." To which Rowena retorts, "Freedom!" Their banter is from Mel Gibson's Braveheart (1995).
Jennifer Copping (Sandra Phelan) previously appeared in the episode A Very Supernatural Christmas (2007), as "Mrs. Caldwell".