The first two hour season finale since season 6.
Dean says "We're going to straight Shawshank this bitch", referencing the movie The Shawshank Redemption, in which a prisoner escapes by slowly digging a secret hole in the wall of his cell for years, in order to escape through the sewage system.
Dean says he always imagined he and Sam would go out "like Butch and Sundance," referencing the movie Butch Cassidy and the Sundance Kid, in which the titular characters go out in a blaze of glory, running headfirst towards their enemies, despite being greatly outnumbered.
In the episode, Dr. Hess calls Sam "Dean" by mistake, and Sam corrects her. This could have been a nod to Gilmore Girls (2000), where Jared Padalecki plays a character named Dean.