As everyone may know you can change the layers on any flatworld. I ran into some bugs and glitches in them. Here are a few. Playing with my friend justa bitofnotch and in the flatworld and he took out the dirt. Not the grass or bedrock.
Everyone of the villager houses was one block up to where no villager could get into their house if they came out. Another glitch was when I made a flatworld and removed all layers in the desert flatworld, but not bedrock. There was random floating mineshafts in the air everywhere. Experiment with removing layers and find your own bugs and glitches on your own and comment about them and tell me. Now if only we could add layers with just tnt. Still then the problem would be the explosion would never stop because the worlds never end causing SO MUCH LAG!