As Metatron begins his all-angel broadcast, his voice echoes dramatically. His assistant, Neil, says, "More reverb" to which Metatron replies, "Because I'm Lou Gehrig?" Lou Gehrig, forced to retire in 1939 because of his recent ALS diagnosis, delivered his famous "Luckiest Man on the Face of the Earth!" farewell speech on July 4th in a packed Yankee Stadium, with a lot of reverberation.
At about 29:10 minutes in, Dean says to Metatron "Hell, I'm blaming you for the Cubs not winning the World Series in the last 100 freaking years." In 2016, two years after this episode aired, the Chicago Cubs would go on to win the World Series for the first time in 108 years.
The song that plays at the end of this episode is "Can't Find My Way Home" by Blind Faith. While songs like these are chosen carefully, Supernatural sometimes unintentionally wraps around to one of the first themes in the series: the ghost that repeats, "I can never go home" from 1x01 Pilot (2005) which mirrors Sam and Dean's struggle to find a true home (beyond the meaning of a building that they live in, but a place with family and safety) throughout the series.
This title of this episode is actually a reference to the song (of the same title) by Slade the line from Fleetwood Mac actually says "I never did believe in miracles"
Before being replaced with "Line of Love" by The Minors due to licensing issues, season one's Route 666 (2006) featured "Can't Find My Way Home" by Blind Faith, which coincidentally was also used in this episode nine years later.