Dean: What, did angels invest in Deloreans?
A reference to the time traveling Delorean in the movie Back to the Future. There are other references to the movie in this episode, such as Dean meeting his father's younger self in a diner.

Dean: Nice threads. You know Sonny and Cher broke up, right?
Young John: Sonny and Cher broke up?
Sonny and Cher were a popular singing husband and wife duo. In 1973 they had an Emmy award winning show called The Sony and Cher Comedy Hour.

Dean: Know where I can get any reception?
Young John: The U.S.S. Enterprise?
To young John Winchester, Dean's cell phone looks like a communicator from Star Trek

Young John: John Winchester. Thanks.
Dean: Dean Van Halen.
Dean introduces himself as Dean Van Halen. Van Halen is a rock band who enjoyed their first album success in 1978.

The VW van John Winchester nearly buys instead of the Impala is possibly a shoutout to the mode of transport known as the "Mystery Van" used by the Scooby gang in Scooby Doo

Dean and Samuel appearing together in priests' outfits harks back to Dean and Sam doing the same in 1.14 Nightmare.

Azazel: You're Little Orphan Mary now.
Little Orphan Annie was an character in a comic strip that started in the 1920s and later made into movies and a hit musical.

Mary deals for John's life on May 2. This is Sam's birthday. It is also the same day John Winchester traded his life for Dean's and Dean traded his for Sam's and the day Dean went to Hell.

The scene were Dean first meets young John Winchester in the diner is almost identical to how and where Marty McFly first meets his teenage father in Back to the Future

When Dean and Samuel run into each other at the Whitshire home dressed as priests, Dean introduces Samuel as "Father Cheney." This is a reference to U.S. Vice President Dick Cheney. There was a previous reference to Cheney in 3.04 Sin City.