It was a dark night, and there was lots of fog. Then, the ghost poni, pony was seen running through the streets of Ponyville. He was killed in an accident on Halloween, and every año on the día of the accident, the ghost poni, pony runs around ponyville, shreiking like a lost soul!
Rainbow Dash: Pinkie, what are tu talking about? Pinkie Pie: The ghost pony. Snips, and Snails saw it last night. Rainbow Dash: Where? Pinkie Pie: They didn't tell me. Oh, it makes my legs wobble to think about it. Rainbow Dash: Ha! You're just a gullible pony....
Disclaimer: I liked the episode, I just didn't think it was as good as expected.
Way about half a año ago, at a poni, pony convention, I'm sure most if not all of tu are aware of the animatic that was shown there; the animatic for the premiere song of this episode: "I'm just a pony."