[Spoiler (click to open)]The music, the cinematography, the monsters (this, more than alternate universes, is the kind of worldbuilding I'm into), mohawk trucker lady(!!!!!), Bible guy, clown-like mask dude whose FACE WE NEVER SEE(?!), the fight choreography, Sam's bedroom, their shitty pancake mix, Donna, Doug, the works.
Loved the sly Impala callout, too. I'm PRETTY SURE that was a mid-2000s variant. Dean definitely noticed. XD