This episode wins. This episode wins all the winning units.

The Shining reference
Metal Gear Solid reference
Senior Huevos
Discord's Chaos Realm full of Eldritch Horrors
Gallagher, Eddie Murphy, and Jerry Seinfeld references
"You're the most basic of jokes". Also pretty much anything else Maud said
College confirmed to be a thing that exists in Equestria
Making fun of Twilight's flying abilities
Trollestia
ALL the cakes. ALL of them.

Best episode, Season 5 confirmed best season.

That is all.