If you summon a minecart using
[code] /summon MinecartRideable ~ ~ ~ [/code] or [code] /summon MinecartRideable ~ ~5 ~ [/code], or push a minecart of the rails, it will fall through the ground and end up 0.5 blocks lower then it should be. It's actually at that point, not just visible. I am not able to check if it's visual or not, I hope you at Mojang can do that for me