Hopefully the little fella is just shaken, and not stirred.
Seriously, though, I hope it's alright. I'm learning about these guys still, but from a physics viewpoint (F=ma), how big is the turtle? Bigger means more weight and more force with which to land, but also means a thicker shell. I'm sure it is fine, though.
When my son was 4 he was temporarily banned for turtle chucking at the local kid's museum. The adult turtle he tossed was fine. I do not recommend this, by any means. And don't be hating him for this, he was very young and learned never to do it again.