First of all, I love the new carts. They really add a good visual to the game. Good job!
My suggestion on the carts though is that maybe if we could get them to reflect how much is in the cart. Not numerical, but visually. Like, if you're a level 5 castle, you won't have much, so maybe the cart looks mostly empty. As you progress, maybe every 5 castle levels, the cart looks more full. So at castle level 40, the thing is packed full and nearly overflowing.
This is purely visual, and it's actually fine the way that it is, but it would be a type of sense of accomplishment when your carts look more full.