The Mane 6 take a look around. "Isn't there supposed to be a puzzle here?"
Applejack looks around. "Well, I don't see one. Maybe it'll show up if we wait a bit. Hey, why don't we play a game to pass the time?"
"I promise it'll be quick," Applejack says, as she starts shuffling two decks of red and green cards. "Hang on, are we missing a few cards?"
Hints are available here.