One time I had the rocket launcher, and for some reason all the rounds were duds. No explosions occurred at all. Weird.

Another time I turned into a ghost somehow. Nobody could see me for some reason, and whenever I shot someone it caused no damage. I ended up running around knifing people, and I could here them freaking out because they knew they were being stabbed, but had no idea where it was coming from. Even though I couldn't hurt them, I am pretty sure I disrupted them from shooting other players.

Anybody else have any weird glitches?

one time when i was driving the car in single player, i actually fell through a building into the cement cuz i guess it wasnt done loading... wierd

Only glitch I've ever encountered was this one certain spot where if you walked over it, you would fall under the map, and then shoot back up about 30 feet away from it every time.

There is a cargo container that if you get someone to hang on the left door and drive into the right door.(left door shut , right door open) if done right the person on the door ill go about 100ft in the air and fall anywhere on the map. This will make when land on buildings , boats , cars , water ect. The person in the car however will fall into the floor and can swim, walk , run , drive ect. under the map. He can also shoot people under the floor and as far as i have tested this out , with a AK47 under the floor it can blow up Jeeps and Helicopters in one bullet but that could always be a fault

Bugged out while riding a 900 once so my character disappeared... so everyone in the game saw a phantom bike running around without a rider.

multiplayer is one giant glitch. R* didnt put much time into it seemingly. not very well thought out.