If a Minecart with TNT is hit with an arrow, fire charge, egg or snowball that was thrown/shot via a Dispenser, it will crash the game. Doesn't work with splash potions or other items are dropped by the dispenser.

Steps to reproduce

1. Place a dispensor facing a TNT minecart (the TNT minecart can be on any rail or not, doesn't matter)
2. Place arrows, eggs, fire charge or snowballs into dispensor
3. Activate the dispensor any way you like (redstone, button, etc.)

Device used to crash the game here: http://imgur.com/GMgtM8O Simply place Tnt minecart on detector rail to crash game.