When Fluttershy gets upset at herself for not being able to fly fast, she cries and runs away. Rainbow sees how hurt the timid pegasus is and chases after her. She ends up teaching her a valuable lesson from when she was a filly to show that just because you can't do something right now, doesn't mean you can't do it in the future.

This is an alternate scene to "Hurricane Fluttershy" when Rainbow chases Fluttershy instead of going back.