This code is VERY glitchy, and I feel like it has an unused 2 player mode???????????? (Probably not, I'm not an expert) Can an expert explore it? I tried on my GBC and I died in 2-1, then you can press select on the title screen to go down and when you do, there is no music, you are in the submarine or plane, and all the graphics are glitchy
Soon as you come to level three... jump up against the wall. (like take one step then jump). then there a box will appear, jump on the box. This will take you above to the top, and get like a bunch of coins
On completion of the game, press any button at the title screen, the cursor should then change to Mario's face. If you press start to begin a new game it will be at Expert Level with more enemies which are harder and come from different places.