After examining the 3-D images more closely, I noticed a few peculiarities:
Elevator Stage
The fireball is hanging out on a small, isolated platform. How did it get there? Did it somehow jump the gap? If so, that's a nice trick. It would make the stage a little more interesting. If firefoxes had that ability, L5+ rivets would be more of a colossal nightmare than they already are.
Rivet Stage
What's the purse doing on the left side of the 3rd girder? I'm guessing that Mario is a more shady character than we realized. He picked it up on the bottom level, took the cash and credit cards inside, and ditched it somewhere else. He's a slippery one.
Both hammers are on the right side of the screen. That's great news! From now on, I'll be using the weave pattern almost exclusively.