Tip: Switch palace switches normally disappear if you replay the level. However, if you insert them as direct Map16 and use the hex-edit at $00EEB2 in the ROM map, you can replay the level without a problem.
I was having a problem where sprites were facing right at the start of a sub-level if Mario entered from a higher screen number than the one the sprites are on. This patch seems to fix that as well, very useful when using enemies like Spike Tops. Thanks!