The Dog

I’m guessing the writers needed some way for Mario and Luigi to be failures at their plumbing business, but the scene involving the dog was so forced.

No dog would react with that much rage over someone stepping on their biscuit and breaking it in two. They would just eat the rest of it.

Even if they did, it’s the client’s fault because they didn’t lock up their dog while the two men got to work. It was their own negligence that resulted not only in their bathroom being damaged but also put Mario and Luigi’s (and their own dog’s) lives at risk.