I've seen those on the PC too, but here's a glitch for you. Now my brother is the only person I've seen to accomplish this hilarious glitch in the sewer/river (whatever u want to call it) part in LA. First of all, the glitch occured because my brother and I was BS around in the LA. Evenually we ended up in the sewer and my brother was driving his car and had it on two wheels. All of sudden, he makes his car roll on its back and starts to slide on the water.
Just when his car was about to stop, the car explodes and (I'm frinking serious here) shoots up like a rocket to the top of the screen. If you were to look at his screen, you could literally see the entire map of LA. "Holy S***!!", I exclaimed, because it was the craziest thing I've ever seen. The crash was just as funny as the car came crashing down exploding like a bomb, man that was some funny s***.
I don't know how the hell he keeps doing it but I've tried it and my friends are trying to do it but it seems he's the only one AFAIK that has done it.