Atlanta#1: Get on the highway and look for a spot in the wall that looks smeared. get on 2 wheels and drive through. It will take a few tries but its possible. (easier with motorcycle)
online#1. You'll need 6 or more people in your game in order to do this. The first thing you need to do is restart the game but hit X 4 times really fast and if u did it right, everyone (but you) will fly into the air.

NOTE if u are using hydrolics and in the air and the glitch happens, you wont fly.

Online Tokyo#1: Turn sideways into the garage and go fast and you will go through the garage.

Online Atlanta#1: Go to the mall. Go on the top floor and (make sure you have a car with hydrolics) hop your front onto the wall. get a buddy to push you up with your back up and front on the wall. you will respawn in the air.

No San Deigo or Detroit glitches that I know of yet. Ill post them when I know about them.