While the morbid humor is the initial appeal...
It ends far too abruptly. These kind of chain reaction type scenarios are best played out when a number of things happen, not just two or three. Overall it was a good effort, the humor managed to be dark and violent without resorting to the "corn factor" of mindless cursing and poop and pee jokes. I think the overall visuals were perhaps a bit too minimal, but you did a great job on making it look "old timey"--the kind of pulsating/glowy effect was really well implemented.