Ive found a glitch. When you make enough slices to juuust come to the flag, where you neither have more or less than is required, the game doesnt seem to know what to do. It messes up and allows me to place another slice, but the slice doesnt actually cut anything and the level doesnt finish. The balls are able to bounce through the slice as well, and it doesnt restart the level.
It's nice that it gives hints at how to do the level, but it should be something that u can click on. I find me self resarting the level because of small screw ups and eventually getting told exactly how to do the level.