These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Breather Level: In the Flash version of World 3, Island Express has only platforms, Squiggles, and stars, leaving out the enemies and challenges present in other levels. In the console version of the game, however, that stage is a full, fleshed-out level.