I'm afraid it's not as good as it seems. In fact, you're both right. Stage 2, 4 (pic 2), 5 and 6 - just switch TERRAIN and OBJECT from 'STAGEX' with that of 'STAGE0' and you can freely fly around the level by selecting Mike's Room. Although it really is just to see the level design, as no events are triggered. Stage 4 (pic 1) - You can remove the PATH/PATH.MIFF which will activate the enemies / buildings of the level. You get a good minute of battle, fly over the hill, and just as you're about to pat yourself on the back, you're shot straight into the floor, heh. It is strange that they're a part of the same stage, but they do flow into each other in a way that sort of makes sense. I swear there must be more to find in Stage 4 though, because it's a pretty short level otherwise. I'm just not sure if I'll be wasting my time flying into endless 'fog' if I go looking... You'll see what I mean when you try it out.