This glitch occurs on the Xbox One Game Preview. So, when playing on multiplayer, the game gets increasingly laggy when the number of players increase. This is somewhat tolerable, but when a player who is NOT the host enters and controls a vehicle, this will drop the host down to about 5 Frames Per Second (FPS) and ultimately crash the Host's game, booting all players from the world. Thus making the desire to play multiplayer a minimum.
This glitch occurs on the Xbox One Game Preview. So, when the player presses X to equip the 'Terraformer' (the thing that makes, destroys terrain) then clicks LB or Left Button to switch to the build setting, and builds land so it encases the avatar you will notice that the player who was encased inside of the pile will fall through the world, and if controlled correctly can stay under there as long as they want to and basically 'fly' underground.