In the part of the game where you have to push the mining cart down the hill to break through the wall, the first time I tried it something happened and the cart rolled off of to the right when it reached the end of the tracks and did not break the wall. It turned over and of course it is too heavy to push back up the hill anyway. I think I may have put a rock on top of it before rolling so but can't remember for certain, but if so that may have had an effect.

Luckily I reloaded and tried again, since I was pretty sure the cart was supposed to break the wall, and it worked the 2nd time. But, I could see a situation arising where someone would experience this, think they are supposed to do something else, and get stuck