Minecraft wiki entry for Infdev_20100327_to_Beta_1.7.3, associated text: When travelling away from spawn, every time the distance is doubled from the center of the world, there is an issue with precision, where entities and block hitboxes (where the block should be) still match the shape of the world, but what we see (the blocks) don't. This effect can first be seen at 65,536 blocks away from spawn if observed closely, even though it is far less noticeable than what is seen when the player is close to the Far Lands. Past 8,388,608 blocks, the offset is an entire block, which is the extent of the effect seen at the Far Lands.