During one of Dean's memories of being a kid, Mary asks him if he wants some pie. The implication being that his long standing affection for pie is rooted in associating it with his Mom & happier times.
This episode has multiple Disney references. Ash continues to compare heaven to Disney World and the Magic Kingdom. The two hunters who kill Sam and Dean are named Walt and Roy (Walt Disney's brother's name is Roy).
Zachariah says that in Heaven he has 4 faces one of which was a lion, this would make him a Cherub. In the Christian Angelic Hierarchy it is the Cherubs' job to guard the way to The Garden of Eden as well as God's Throne, which is exactly what he is doing when he stops Sam and Dean from entering the garden.
When Castiel tells Sam and Dean "Don't go towards the light" and Dean replies " OK thanks Carol Anne" it's a homage to Poltergeist (1982). Also Castiel is speaking to them through a television set.
While discussing various historical figures, Ash mentions Mallanaga Vatsyayana, the Indian mythical sage of the Asuras (demigods) to whom erotic sciences and, in particular, the Kama Sutra, are attributed. Ash's pronunciation is extremely misleading, but he does get the name right.