I've been playing Super Mario Bros. 3 for years, and I used to think it was a perfect game. Today, though, I realized it does have one flaw: world 4 is easier than world 3.

The difference isn't huge, admittedly, but I still say world 3 is a lot rougher. It's bigger and some of the levels are definitely more vicious, requiring more attempts to clear than anything in world 4 really does. The battleship at the end of world 3 is tougher, as well.

Through and through, world 4 is simpler. So the order is backwards of what it should have been, perhaps even backwards of what it was going to be when the levels were originally designed. It's not a big dent in the game's armor or anything, obviously, but it is there. So yeah, Super Mario Bros. 3 isn't perfect (just insanely close).