Continuity mistake: When Raphael meets Yoshi and talks to him about being a kid and having fun, if you look at Raph's wrists you'll notice that he is not wearing any wrist bands as he usually does as with the rest of the turtles. However, when Raph puts his hand on Yoshi's shoulder there is a close-up of Yoshi's head and shoulders. Look at Raph's wrist in the close-up and you'll see that a wrist band has appeared. When the shot changes back, his wrists are bare again.
Other mistake: After Leonardo revives Yoshi, he picks him up, hugs him and touches heads with each other as they hug but Yoshi pretty much moved his head immediately and Leonardo continued sitting there as if their heads were still touching. It looks like the actor didn't realise the child moved away and they never reshot it.