Minecraft wiki entry for Minecart_with_TNT, associated text: The first image of minecarts with TNT, released by Dinnerbone.[5][6] (One can be seen in the lower-left corner.)
A more zoomed in image.
Minecart with TNT and activator rail for detonation.
The 13w02a banner, with a minecart with TNT and a hopper.
Dinnerbone showing how minecarts with TNT have controlled explosions.[7]
Primed minecart with TNT.
Explosion from a minecart with TNT. (The "bridge" of rails is left undestroyed by the explosion.)