This is the first season finale to feature the song "Carry On Wayward Son" by Kansas. It was previously used over the original montage of 1.21 Salvation (2006) (though on Netflix that particular instance of the song's usage had to be replaced due to licensing issues). The song has gone on to be used at the beginning of every season finale since then, and has come to be regarded by fans as an unofficial theme song for the show.
For Dean's monologue to Sam lying dead on the table, Jensen knew he wanted to play it extremely intimate and emotional. He spoke to the director before they filmed, asking how he intended to film it because Jensen knew that he wouldn't be able to do too many takes. To accommodate him, the director closed the set to give Jensen privacy, and placed two cameras and different angles. They did only two takes: one for close ups and one for wide shots.
Azazel tells Jake, "Be all that you can be!" That was the official slogan of the US Army until 2001.
This is the highest rated episode of season 2.
With an average viewership of 3.14 million per episode, Supernatural (2005) was on the verge of cancellation before The CW decided to grant it a third season. The fact the show was selling well on DVD was one of the deciding factors.