Actor Allusion: Trixie creates a window in space to view past events and uses a spell like a computer GUI to remove Pinkie's mouth. Trixie's voice actress, Kathleen Barr, also voiced Dot Matrix on ReBoot, a show where such things would have been commonplace.
A common story for Trixie in fanfiction is that, after the events of "Boast Busters", she became a laughingstock and was unable to go anywhere with her magic show without being laughed out of town. This episode officially canonizes that.
The term "Alicorn" is used, which is the term used by the fandom for Winged Unicorns (even though the word actually means "unicorn's horn"; more on that in a second). Indeed, the Alicorn Amulet takes the shape of a Winged Unicorn. Given the context in which it is used, however, it can refer to both a Winged Unicorn and the material that a unicorn's horn is made of, as it is increasing Trixie's unicorn powers. (The show would later use the word "alicorn" to specifically refer to the species.)