So while working on my add-on resource pack, I noticed that there's a misplaced Toadstone block on the outside of the castle. If you were facing the entrance, it's to the right.

Additionally, some fortresses in the Mushroom Kingdom have stuff on the outside that I don't think should be there. Pipes seem to be the most common issue, but this one has mushrooms on it as well. It looks very weird when most fortresses in Mario aren't depicted with stuff on the top of them.