A simple Tunneler drone is catapulted from Equestria during the infamous Wedding onto earth. Confused, injured and alone, the drone must figure out how to survive with the whole world watching. (Changeling on Earth, Xcom, Men in Black and SG:1 Xover)
Humanity's space exploration ultimately took the form of billions of identical probes, capable of building anything (including astronauts themselves) upon arrival at their destinations. One lands in Equestria. Things go downhill from there.
A dying young man discovers that his life may not be what he thought it was, and the seemingly innocent TV show he watches in his hospital room may not be fictitious.