Inifinite 3D with Mario.
Beat Flopside Pit of 100 Trails twice and get Mario's Card. This will allow you to go in 3D for as long as you want. this was at gamespot.com if i helped you rep me
I was confused too. I noticed the unlimited 3D flipping when I was in chapter 8. I thought it was some kind of magic. But I noticed that again replying chapter 1-1. Now I know where I got it.