Dean mentions Sam's imaginary friend who was revealed to be the zanna Sully ( Nate Torrence ) in Just My Imagination (2015).
In the flashbacks, Dean is almost 14 while Sam is 9. It is also two years after Sam learns the truth in 'A Very Supernatural Christmas.'
This is the second episode to feature an unfinished hunt from the brothers' past, the first being Something Wicked (2006) in Season 1, involving a Shtriga but it's the third episode to feature an unfinished hunt in general, the second being Safe House (2016) in Season 11, involving a Soul Eater, being from Bobby's past.
In 2017, the state of Texas basses a bill making it illegal to text and drive across the state. Jenson Ackles did many commercials on the radio talking about the new law.
This is a reference to Toto's song called Africa. It can also be a reference to the song of the same name (from the album Automatisme Psychique) by Act Noir.