In a September 2013 presentation held by Hasbro Australia, a slideshow was shown depicting upcoming My Little Pony and Equestria Girls merchandise. One of the slides in the slideshow relating to Rainbow Power contains the text "QUEST FOR A KINGDOM".
At the beginning of the film and its chapter book adaptation My Little Pony: Equestria Girls: Through the Mirror, Twilight Sparkle worries that, now that she's a princess, Princess Celestia will expect her to lead a kingdom of her own, a possibility that Spike gets excited about.
Twilight and her friends are seen in the Castle of Friendship, gathering books for the castle's library, when suddenly Twilight notices a book vibrating. The book has Princess Celestia's cutie mark on the cover. She opens it and finds out that her friends from Canterlot High School are in trouble. Through research, she discovers that three sirens were banished to the human world by Star Swirl the Bearded. She makes some adjustments to the Crystal Mirror from the first film to make it able to open at any time, as opposed to every thirty moons.
In the half-hour special, Pinkie Pie makes a sculpture of the Castle of Friendship out of chocolate.
In the half-hour special, Sunset enters the castle through the mirror, where she meets Starlight Glimmer.
The castle briefly appears in the Rainbow Rocks film screenplay novelization My Little Pony: Equestria Girls: Rainbow Rocks: The Mane Event.
- ↑ Ossie (2014-04-04). EqG Rainbow Rocks Early Concept Art + Rival Band Name. All About MLP Merch. Blogger. Retrieved on 2014 April 8.