S03E33 - Rangers in Reverse
Synopsis
It's Kat's birthday so the other Rangers take her to a surprise outing at a theme park. Whilst this is going on Master Vile sends Rito down with the Orb Of Doom. The Orb's power will make the Earth rotate backwards making everyone on the planet younger.
The Rangers try to stop Rito but fail and they become young children. To make matters worse they are powerless. Rita, Zedd, Rito and Goldar make themselves grow and start rampaging through Angel Grove...