After making a terrible mistake with time travel, Twilight Sparkle begins to fade from existence.

But not before using the opportunity to advance the cause of science.

Pinkie's tail is a lot bigger on the inside, and certainly will keep three fillies hidden when they get in trouble, but is it really so easy to get out? They certainly think so...
Takes place sometime during Season 4 (before Twilight gets a castle).

Made for Matthewthawes as a fic request.