"Dr. Kripke", the doctor who attends one of the Winchesters on an emergency at the hospital, is a reference to executive producer and sometimes writer Eric Kripke. He is also called to room 237 for a code blue. Room 237 is significant in "The Shining" (1980)
Tessa is the first reaper seen in Supernatural in a normal human form. The first time a reaper is shown is in the season one episode Faith (2006). The Greek meaning of the name Tessa is "reaper".
First appearance of Tessa.
After ghost Dean breaks a glass in his father's room, he says: "I full on Swayzed that mother". This is a reference to the movie Ghost (1990) in which Patrick Swayze's ghost character only manages to move something when he gets angry.