So, here's a bit of a funny glitch. Note, I found this on accident after constantly missing keys in certain stages.
It seems you can play to a point, save, quit to title, and start a new game. Now, you might ask what this does. Nothing! ... At first. Get a game over, then continue. Suddenly you have your stats from your save at the beginning of the game. All stats and keys are inherited. New Game+ glitch for those who want to power through and laugh, I guess? I'm using the 720 version, so I don't know if it's somehow exclusive to that or not.
Okay, I think I get WHY it does it. Due to how the game saves and stores stats, getting a game over after starting a game and hitting continue causes the game to grab any saved stats. Since starting a new game doesn't cause the game to save, nor does a game over, your old stats get pulled instead when you press continue.