This is how to get out of the map in the Simpsons: Hit and Run. Note that this method only works in levels 1, 4, and 7.
This glitch allows you to leave, sometimes go underneath, the map. To do this, you will need to enter cheats to make your car jump (Cheat codes are in detail at the bottom). First, drive to the draw- or truss- bridge in level 1 or 4 (level 7 only has the truss). Turn towards the water on either side. Drive to the edge of the bridge or water, and make your car jump. If you go out far enough, you will pass through the water and on to an invisible surface. You can now do one of three things: Drive into the killzone to get back on the map, keep driving outwards and try to breach the sky box (It's actually a sphere in this game :D), or get out of your car and fall forever. Oh, and you can also quit. This glitch has no side effects on your normal game.
Why it WorksEdit
When you jump far enough, you pass the killzone barrier in the water. At this distance, the water is just a texture, and so you fall through. I can not explain, however, why you land on a surface.
There is 1 thing that tries to prevent you from breaching the sky box (sphere). It is the fact that once you go out far enough, your car starts randomly bouncing. This is due to the loss of precision as the limit of a 32-bit floating point number is reached. While it is bouncing, you cannot drive in any direction. One option is to keep jumping, but it is very hard to keep yourself in a straight line while the weird physics mercilessly bounce you everywhere.
I found this glitch myself, but it was probably discovered by many other people, too.