Invisible walls, losing all momentum randomly, projectiles veering off course, getting trapped in mid air, all sorts of p00p.
Honestly the invisible walls and momentum loss ruin the entire game, once I tried to hit a jump for a shortcut but the game insisted that the ramp for the jump contained a wall, therefore stealing all of my speed and planting me in the mid-section of the jump itself. Afterward I was stuck till I quit the game.
I've heard that most of these problems are specific to the Wii-U version and it's possible they've patched some of it by now but you should really just avoid the frustration and get it for the PC if you can.
The graphics are great if not awesome however game control is simply unrealistic. If you are an avid gamer who grew up on the joystick then maybe you wii do ok. Unfortunately some of us prefer just normal driving mechanics and this game fails to deliver. You are forced to use the WiiU Gamepad if playing solitary, not a bright idea SEGA.