My call on that is, that the hole is small that the liquid is pouring through thus keeping the liquid backed up. It is not a freepouring container, so it would take a while to empty. And based on the angle Bones is pouring it, it would still look full until a greater amount had been poured......
Another thing to keep in mind is that Bones is holding some sort of cloth over the upper portion of the bottle where the liquid would be moving and slanting while being poured so it gives the illusion that nothing's moving inside the bottle.