If you still have that old PS2, Xbox, or GameCube, get it out, along with your copy of Lego Star Wars, you can do this glitch pretty much anywhere in the game, when you are in front of a transition trigger, push one of the NPCs past it then switch to them, and bam! you're out of bounds! It's a different room for each spot, so there might be basically nothing there, depending on where you do this.