Go to Flint County. There should be a road to follow. Drive on it, and you will see a wall that leads off the to the side. If you drive up and down that wall, you should fall through the ground. You may have to do it a few times. You must hug the wall for this glitch to occur. Additionally, go to your safe house in Prickle Pine. Enable the "CJ jumps higher" code. Enter the safe house. Turn towards the entrance and jump up. You should go over the wall and fall into blackness until you land in a field of grey. In front of you should be an incomplete version of the are where you saved Denise. Buildings will be missing, but you can physically touch them. You should also see white letters that read "Ganton", "North Rock", and "Downtown". Stand in front of it and mark the Four Dragons Casino. Then, enable the "Spawn Jetpack" code and fly it toward the casino. You should eventually see an armor pickup, a uzi pickup, a pistol pickup, and a money pickup that contains $15,000 at most. You should also see four white doors, but they have the wall physics around them.