Title screen music modifier unused Superman Theme
That's right, the Superman Theme song exists in the Game Boy game!
Elmar Krieger arranged this version and I don't know why he didn't use it as the title screen since it would have been fit. My guess is that this was intended for an ending but the game does not have a proper ending and instead shows a generic "Congratulations! message with the stage clear theme playing.
Why was this not used? The world may never know, and you can't spin the world in reverse to turn back time and find out.