First things first, I have to say; I LOVE the game. I've always loved these kinds of simulation/shop management games, and combining that with the whole RPG world of making weapons is an amazing concept. Obviously, since this is an alpha build, there's going to be a lot of bugs with it.
I don't know if any of these bugs have been mentioned before, so blanket forgiveness if I posted a repeat. This is all on version 0.0.82
The physics are... clunky, at best. First of all, as people have mentioned, the whole flying horse cart bug is a serious issue and it needs to be fixed. I've spent the whole game just walking as it's not worth the restart to use the cart. Second, you can literally fly up into the sky just by standing underneath an object and holding it, it's a fun bug, but that does need to be fixed as it can get quite annoying as it can send items flying as well.
Next are the crates--sometimes the items you put in the crates will get stuck and you'd have no way to pull it out, it happens a lot when you buy parts from the parts shop. Actually, a lot of items can get stuck in various things, and that's somewhat frustrating.
Then there's also a bug where you can still run even when the game prompts you that you're tired. You can do this by pressing shift while holding an object, it only lasts for a couple of seconds, but you can spam the shift button to run indefinitely.
I believe those are the only bugs I've found so far? Is the coin chest supposed to actually have coins? Because I haven't seen any coins at all, maybe it's removed and I just didn't know.