Board Thread:Questions and Answers/@comment-24728184-20140313185356/@comment-1362555-20140603040941

Leofan13 wrote: There was an episode in the 80s series where the Turtles did turn back into regular turtles. They got hit with Shredder's retromutagen ray gun (I forget the exact name he gave it) and Splinter had to save them.

You misremembered it. Splinter did save the Turtles, but he destroyed the retro mutagen ray before it could be used on the Turtles.