I was confused about why some of the black lines are solid and some, the guy just passes through. So I read a bunch of Line Rider tutorials, but they said the only possible colors for lines are red, blue, and green, and now I'm even more confused.
Line rider is full of bugs. Very fun and useful bugs. Going fast enough or at the right angle or nearby something or ... will let you clip through things, accelerate uphill, spin instead of moving, etc.
The red, green, and blue lines are those colors when editing, so you know what type they are. When you hit "play" and are viewing the rider ride the lines, all lines are black.