When a minecart is travelling on a track that is powered by a powered rail every now and then (so that the minecart doesn't travel too fast and derail at a corner) and it goes to travel up a hill, the minecart can come to a sudden stop and then travel backwards on the minecart.

What should happen is that the minecart should travel straight up the hill and not stop.

What does happen is that the minecart stops travelling up the hill at any given block and travels backwards as if it's hit the wall.