Here's one fascinating glitch I accidentally found, it's in the "Conspiracy" level I think(level in a building with a laser wall, men in black, and maids.). To do this trick, simply hide on a wall or in the bathroom, someplace a bit less conspicuous, use psychic ability Projection, go out and find a guard or a maid, and then possess them by having your glowing blue light walk up to/on them and press A. Where you want to go is, at the beginning of the level(with the guy at the computer you freaked out and killed during the cutscene), go down the left corridor and there're two guys playing some weird "E" word game behind a laser wall. Possess someone, go around so you're behind the wall(the right corridor from the start), and you'll see two elevators. Simply waltz up to one, press the button, and, if you have enough time and psi energy, enter the elevator when it opens up and wait for the door to close with the person in it. After about a minute, the person will disappear. No, they didn't walk out (they don't normally), but they vanished completely! Seriously, my projection was once in the elevator with a guy and he suddenly disappeared. Cool, huh?