There were all types on crazy gadgets in the original TMNT series. Every episode had either Shredder, a mad scientist or a gangster attempting to steal some new, ultra-powerful device. And whatever it was that the villains stole, Donatello would always have a gadget of his own that he'd pull out of nowhere to counter it. As if he was at one point able to see into the future beforehand and knew exactly what gizmo the villains were going to use.
Anyone remember the "Attack of Big MACC" episode? Mere minutes after the MACC robot appeared from 400 years in the future, Krang had already produced some gizmo that - when attached to the robot's neck - would someone allow this unknown, futuristic robot to be controlled for evil purposes. So Shredder responds the same way any intelligent viewer would have:
"This is something you just happened to have laying around, right??"