An orange hoof knocked on the door to Fluttershy's cottage. When she opened the door, she was shocked. Mainly at seeing another version of herself, the retired Princess Luna, and two copies of Twilight. Once she got over that surprise, she noticed most of their pony parts were wrong.
"Why are all your pony parts wrong?" she asked.
"That's what we're here to find out," the Twilight with no wings replied. She took a deep breath, and both Fluttershies covered their ears before she shouted through the doorway, "Disco-o-ord!"
"Oh…" Pony-Fluttershy murmured. "He's, um, not here…"
Everyhumanpony else sighed.
"Yeah, figures."
"That jerk."
"Why does he always have to be involved in this…"
"Balderdash?"
"Precisely."
A shadow responded, "I could ask the same, ladies." Everyone looked, and saw Discord smoking his way out of Pony-Fluttershy's mailbox.
"You!" Pony-Twilight pointed.
"Me!" Discord pointed. "Me. Why is it always me? Why don't you bother, er, what's-his-face, or what's-her-mane, instead?"
A shout almost started from the crowd, but Pony-Fluttershy cleared her throat, which earned some silence. She took a step towards Discord and spoke clearly, "Um, well, it is, usually, your, um, fault, when these things, um, happen…"
Discord tied his arms but considered the sparse words. Then he rolled a sigh and breathed his eyes - or was it the other way around? "Fine. I will admit to causing the pony versions of you lot some trouble. But this," - he pointed to the party of pedestrian-ponies with misplaced pony parts - "was not me. I was busy."
"Okay," Pony-Fluttershy said.
"Not okay!" Pony-Twilight said, holding a hoof over Pony-Fluttershy's mouth. "You were busy? With what?"
"I was on holiday in a little seaside resort called Nunya Business."
Pony-Twilight looked at him.
He put up his appendages innocently. "No, I'm serious! That's what it's called. There's ads in the phone book. Don't ponies read, these days?"
"Ugh, fine, maybe you're not involved - this time - but this sort of thing is right up your alley. Can't you help us? A little?"
Discord was no longer in the mailbox. Pony-Twilight found him leaning over her from a perch on her withers. "Your tone is out of tune, my dear, but fine." He extended a bethumbed cat's paw from off-screen and snapped his furry fingers. There was a spark of light, then-
Everyhumanpony looked at themselves. Nothing appeared different.
"Oh," he said. All colour drained from his face and spilled onto the grass, turning it rainbow hues. "Oh, that's, um. Oh."
Everyone asked, "What?"
""N-nothing!"" he said, though there was an extra set of quotes around his closed captioning entry. "I'm sure it's fine. I just remembered, I left the oven on. And the oven is in my other pants. Which are getting dry-cleaned. Good luck, and toodle-oo!"
With that, he folded himself into a letter and stuffed himself back into the mailbox. A cross-eyed mailpony happened to come by just at that instant, and collected the letter as if it was the most normal thing in the world.
She then looked taken aback, as if she'd just noticed the other ten ponies gathered outside of Fluttershy's cottage.
"Oh, sorry to interrupt," she said sheepishly, "but have any of you noticed that your pony parts are wrong?"
"Yes," Sunset said through teeth.
"Oh. Well, okay then! Bye!"
The mailpony flew away.
"Twilight," Sunset said.
"Yes?" Both Twilights said.
"Does this sort of thing happen to you a lot?" Sunset asked.
Human-Twilight started, "n-" but Pony-Twilight stated a firm, capital, "Yes."
"Oh," Human-Twilight said.
No-one said anything for a while.
Noticing the gap in conversation, Luna opined, "If the trickster speaks true, then our transanatomical affliction may be of natural, rational nature. I would consult the Royal Archives were I not quite famished."
Pony-Twilight nodded along, but everyone else gave the two of them the kind of look that indicated they had no idea what she had just said.
"Oh," Luna said, "Pardon me, I still have to practice my modern dialect. Ahem. If'n that ain't a load o' hogwash, we ken try the libary after we get some grub."
"Yeah, good idea," Sunset said, looking at her phone. "We're already late for our reservation, but could they really say no to two Princesses? Er, would that be three?"
"One," all present potential Princesses proposed. Then they all looked at each other with sour expressions.
Sunset sighed. "I guess we'll figure it out when we get there. Le Pâturage… We're not too far, actually. This way, I think?" She pointed vaguely in the direction of Ponyville. "Man, I wish there were satellites here."
Meanwhile, Applejack mumbled to Pinkie Pie, "Do I really sound like that?"
"Like what?"
"Like what Luna just said."
"Oh, that was her?" Pinkie Pie looked between Applejack and Luna.
"...Nevermind."