As Sam is drawing the tree from his dream at the beginning of the episode, Dean says "A fishing trawler found off the coast of Cali, it's crew vanished". This is a possible referral to Benny's (season 8) nest working off the coast of California.
There are at least three Stephen King story references in this episode. The first was in the beginning when Sam first tells Dean about his visions, and Dean calls it his "shining" (The Shining). The second was the clapping monkey toy when the plumber is fixing the garbage disposal (The Monkey). The third was when Sam is trapped in the house at the end and Dean uses an ax to chop his way through the door, followed by a shot of him looking through the hole in the door (The Shining).