When Sam tells Dean he's Lucifer's vessel Dean says, "Just when you thought you were out, they pull you back in." This is a reference to The Godfather Part III (1990) when a retired Michael Corleone says, " Just when I thought I was out, they pull me back in!"
The sign outside the movie theater when Dean first wake up in 2014 days "Now Playing Route 666". One of the stars of the film Route 666 (2001) is Steven Williams, who plays the hunter Rufus in Supernatural.
"The End" is the final song on The Doors self-titled album and includes the following lyrics;
"Of our elaborate plans, the end Of everything that stands, the end No safety or surprise, the end I'll never look into your eyes...again"
"Of our elaborate plans, the end Of everything that stands, the end No safety or surprise, the end I'll never look into your eyes...again"