Physics is like taxes. You can ignore it, but it won't under any circumstances ignore you.

After being criticized for being slower than ponies able to teleport, Rainbow decides that a piddly thing like the laws of reality shouldn't be allowed to stop her from winning a race against Twilight's teleportation spell, and reclaiming her title as the fastest pony alive.

Physics, however, is not inclined to make an exception on her part.