Hogwarts castle has landed in Equestria—and the foundations of the Crystal Empire with it. The stir this caused in both worlds resulted in an exodus of magic and magic-users to Equestria.
The Changeling Swarm was expelled from Canterlot. What happened to them, no one cares. Unfortunately one of them grabbed onto a Guardspony when the Loveblast hit, taking him to a sudden flight.