So there is a softlock in the game that can be achieved by the underwater screens. Sadly, its patched on latest, but it does work on version 1.20 of the game.
How to do this glitch is as follows.
1. Place a pipe.
2. Make Mario enter the pipe.
3. Place the exit pipe right below where the top screen begins. Don't put anything on the top hath, or the level will have 2 screens worth, breaking the glitch.
4. Enter the pipe.
The only thing that should move is the backgrounds glow. I've tested this by accident on the NSMBU theme, but I'm sure it'll work on other themes.