I've noticed that effects always are in front of blocks labeled as NSMB Fake Walls. For example, shooting fireballs through the fake walls doesn't render its trail behind the fake wall, but instead in front. This can be really frustrating especially when trying to hide secrets like Star Exits or other special collectables.
This can be more frustrating if you kill an emeny at the top of fake walls, then the effect of enemy was blocked by fake walls and make it easy to find.


