- Ascended Fanon:
- Ever since it was first mentioned in "It's About Time", Tartarus became subject to fanfics about one (if not all) of the monsters imprisoned there breaking free. In this episode, our villain does just that.
- "Alicorn Princess Discord". Thanks, M.A. Larson! Even more so, consider that M.A. Larson wrote "It's About Time". He's doubly responsible for these events!
- Fans have been calling for Tirek to be brought into G4 continuity for a long time, and fanart and fanfics featuring him are plentiful. Now their wish has been granted.
- Earth Ponies being stronger than the other two tribes was a piece of fanon so common that it was near-universally accepted. It helps that it was established by Word of God or at least Word of Dante, and there have always been things such as only earth ponies plowing snow in "Winter Wrap Up", or Cheerilee and Ms. Peachbottom's epic Juggernaut moments in "Hearts and Hooves Day" and "Games Ponies Play", respectively, as well as Big Mac and Maud's Running Gag of insane Super Strength. It was up to fans whether to take those moments as proof of earth ponies being stronger as a trait of the race, or as the pegasi and unicorns having other jobs in the first case and Rule of Funny in all those others, but now Celestia confirms this as canon when she mentions that "without their strength" (drained by Tirek), they would not be able to tend the land. It also confirms that this strength is due to their inherent magic.
- I Knew It!: Many fans had suspected and/or hoped Tirek would appear.
- Shrug of God: One user asked Jayson Thiessen whether or not Tirek was the Pony of Shadows from "Castle Mane-ia". His response?Jayson Thiessen: hehe
- "Princess Discord" was referenced by a Meghan McCarthy 2013 April Fools' tweet; this is the latest of other tweets she gave out then that were uncannily close to the actual episode content, in this case being Discord's mock alicorn princess getup.
Trivia / My Little Pony: Friendship Is Magic S4 E25 "Twilight's Kingdom – Part 1"