It doesn't appear to have any ill effects, actually, on the system or the carts. However, it will crash the game in progress and, in about 80% of cases, will actually draw graphics stored on the second cartridge on the screen. Also, with a cart out of the slot the screen resolution apparently changes itself depending on the presence (or lack thereof) of a cartridge in the cartridge slot.
The graphics glitchThis is a bug I discovered that glitches out part of the screen. It seems to happen because you dip below the maximum allowed Y-Position, the game doesn't know where to draw the helicopter graphics and so it freaks out. You can trigger it from the ground through a series of Up,Down+1 and Up,1,(nothing),1. Nothing should happen the first time you try one of these input sequences, but eventually, these sequences will make the helicopter rotate, something it's not supposed to be able to do on the ground.
- You will know when the glitch is active when part of the screen starts glitching out. From here, you can fly up a little and press 1 again to cancel the glitch (and imprint the glitched graphics on the screen), or fly too far up, left or right to crash the game to a colored screen.
- My favorite part is that just before you activate the glitchy screen, you can resume normal play, just without pressing 1. Whenever you want, press the button and the game will crash instantly to a colored screen. You can make a savestate at this point, change up the input and play around with crashing to screens of all different colors and tones. It's very entertaining, and you might even get some surprises, like recognizable graphics and sound effect patterns.
Also, fun fact: I had to switch my Frame Advance hotkey from N to Q because of the frequency with which I pressed Up+Left simultaneously for this run.