From my experience most two stroke engine failures are piston related. The piston overheats and expands causing it to seize or detonation burns a hole in the top. The engines tend to lock up quickly when seized which can cause a problem as the wheel will usually lock up also. They don't seem to violently explode into many bits, though it would be more dramatic.
We had an old Wizzer when we kids just sitting in the garrage when we moved there. You could definately see some major damage to the jug.
The base of the main rod was sticking out. Someone could have hurt their leg fairly bad.
Note: We used it to hook onto a tow rope with tricycles, bicycles and a gocart pulled behind one big Ass! Literally!
Poor Ass pulled us for miles!