I also loved The Ancient One's comment, "Curse me for a donkey's bottom." That cracked me up.
It's even better with Splinter's response - "What?"
Like I couldn't tell when Splinter was talking to the ancinet one and the turtles ran off to play which one stayed behind with him for a little while. Or which one first through the rock or who threw that last one that finnished off the demon.
Don threw the big rock. I think Mikey stayed with Splinter - it sounded like him when he got tagged and ran off.
The turtle where like two, they shouldn't have the strength or coordination yet to chuck good sized rocks with accuracy a good distance away, at a moving object.
Apparently, all things are possible with very basic ninja training. At least one of the turtles is even shown as being an ambidextrous rock-thrower.
Something in me loves the line "There's a scary man in that bush!" I don't know why.