Talk:My Little Pony Equestria Girls: Rainbow Rocks/@comment-26802628-20140912153514/@comment-24908786-20140914004738

My theory. Once Twilight got her new castle, like with when Cadance assumed control of the Crystal Empire and the mirror was moved there, the mirror was then moved to Twilight's castle for her to watch over, especially if the human counterparts to her friends in Ponyville needed her help again, including Sunset.