This is my opinion on what might have happened in the episode ' 28 pranks later '... enjoy? Rainbow Dash turned everypony into cookie-eating zombies. And there is one last thing she wants to do to apologise.
After the whole "casting mind control magic on her friends" incident, Starlight wonders how she can ever manage to apologize for, well, for pretty much everything she's ever done.
When Thorax received a message from Chrysalis he is left with two options: Meet with her to discuss the future of the changeling race, or prepare for a civil war.
A pony from Starlight's old village arrives in Ponyville after Starlight was taken in as Twilight's student. To everyone's surprise, this pony's cutie mark is still mysteriously missing. To no one's surprise, he's quite angry at Starlight about this.
After returning from the heady lights of Las Pegasus, all Fluttershy wants to do is relax. One pink filly however, has heard about her pretending to be a scion of the Rich family, and in a case of mistaken identity... Set after Viva Las Pegasus.
Rainbow Dash took her pranks too far. Fluttershy has had enough of her foalish antics and decides to diclipline her in the only way she knows will get through to the mare. Spanking.
Though the Applewood derby got off to a shaky start for the CMC, it all turned out alright in the end, and a valuable lesson was learned. But for their sisters, there are still a few lingering feelings to get out.
Takes place immediately after "The Cart Before The Ponies". Rainbow Dash, Rarity, and Applejack must answer to some very dissatisfied ponies about their behavior in the Applewood Derby. Can they prove they've learned their lesson?
Zesty Gourmand criticizes the Tasty Treat for claiming to be a good restaurant without her three hoof rating. One certain pony has some things on his mind he wants to "kindly" share to the mare.
After the events of "No Second Prances," Twilight thinks that she has pulled off a flawless friendship lesson. Princess Celestia, however, has some choice words for her former student.