There is a property to buy directly above Madd Dogg's mansion in the Mullholland area. You do not have to have buy it; just go there. In the back is a waterless pool and a wall on the east side. Walk up against it and you will fall through an invisible wall and continue falling until you reappear back on the ground. You can use the Jetpack to fly around in blue hell. Go to the building where the mission "End Of The Line" took place, where you killed Big Smoke. This will not work after you complete the mission -- you should be playing a new file to do this. Get a car and ram the wall in the front. You should either break the wall and go through or break the wall and get pushed back from the impact. Then, drive in and you will fall through the ground and end up back on the street. Sometimes your car will disappear when you get put back on the street. If you walk in, you will fall but when you are put back on the street you will not lose any health. Go to the Ganton gym and park a car in the doorway, with the hood touching the door. Get out, jump on the hood, and walk inside. Once inside, walk back out again. You will appear in a hallway. Walk towards the wall, and you will fall through the world. Walk behind the Mullholland safe house to the pool. Face the side that has five windows. Walk into the one closest to the corner. If you do not automatically fall, walk to where the iron support beams end. You will start falling. In a few seconds you will land around the billboard that is in front of the Vinewood sign.
