Mario and all enemies are either set to appear on top of or behind the background layer. In the case of Piranha Plants, they are set to always appear behind the background so the part of the plant inside the pipe isn't visible. Normally, this approach works perfectly fine because the sky is transparent, so the part of the plant outside of the pipe can be seen. However, the water area background is not transparent, so that the water is a different color than the sky. Because of this, the 8-4 water room Piranha Plant appears behind the water background, making it impossible to see. This is also the same reason Mario becomes invisible the moment he enters the ending pipe (he is set to appear behind the background layer when entering a pipe).
The pipe is a strange color because coral blocks in underwater levels use those colors, and both color blocks and vertical pipes are set to use the same set of colors (they share a color palette). The sideways pipe used to exit underwater levels is set to use the same colors as the ground blocks so that pipe does not have the strange colors.
Effective immediately, any submissions using the SNES9x emulator will not be verified. The SMB1 mod team has concerns about its integrity due to its ability to overclock and remove lag frames, which may not be easily detectable. Additionally, we request that all BizHawk submissions avoid using the S
