The guys over at Dustinsoftware.com have discovered a glitch in the Nintendo Wii version of The Legend of Zelda: Twilight Princess that could prevent you from finishing the game. They created the above video of the glitch at work.
They discovered that after the player saves in the room with the big cannon that Link is unable to warp the cannon out of the room because the game claims a man is watching you still, but if you look around no one is there. If you try to leave the room, the man appears at the door and won't let you leave. You're stuck. You can't leave and you can't progress the storyline.
So for those playing Twilight Princess right now, don't save in the cannon room.