Alright, alright.
Tell me, have you seen 3 mine carts parked on the track yet?
Well blow them up, then go to the LOWEST point you can get to. (Left or right of the track, depends on camera angle.)
After that, so strait, make a phew turns. When you see stairs that go REALLY high, you have to go up. Now after that, follow the track, if you got red remote bombs, I suggest you lay one as you go. To kill the cart baddies, otherwise, when you get to small pillars, stop and take a break on them. If you don't, the baddies'll run you over. O_O
So just keep going along this track until you get to the part you fall down... DO NOT FALL DOWN! (Unless you want a custom piece that's down there somewhere.) There should be 4 columns holding a track above your head. Blow them up, and the exit should appear. BTW, watch out for random cart baddies... Cuz once they ran me over when I was going to the exit.