This is a small glitch:
All the ZR-350's I drive have infinite gears. Constantly upshifts and never reaches 5,6,7,8,34905860286th gear. Just keeps upshifting.
My big glitch:
All of my save icons dissapeared once, for about 3 hours. Gone. The little diskette thingies in all of my save houses were just gone not invisible, GONE. I even phoned rockstar and they said it was the first case they've had something like that happen and asked me a bunch of questions to see if I've done anything to cause it. I tried killing myself, getting busted, getting busted while on a mission, losing a mission, dying on a mission, dying on a mission and thus losing a mission and everything and nothing reset it. It wasn't until my fourth time allowing myself to die whilst on a mission (one of Toreno's, I think) that it reset and the diskettes reappeared.
Oh, and I've had the police-car-stuck-in-the-ground glitch happen to me 1000 times, and in Vice City. Actually, almost during every police chase in vice city. That's how i got my record-setting-jump was by going full speed and hitting one of the windsheilds sticking out of the ground.
And Matt, I've had the same glitch with pedestrians landing in funny positions. Some of them are quite entertaining.
My favourite though, is getting a ***-****** wanted level and going near the water whilst on a boat-- preferrably near a cliff/building where cops can jump off of, and somewhere with shelter to hide you from the chopper, and letting the cops on foot jump off the edge and drown themselves-- then shooting or blowing up their drown bodies!