During the mission where you attempt save the man who is trapped in the rapids and held by a log, try to save him just as he is about to go over the waterfall, and as close to the death zone of the falls as possible. When you dive, aim directly for him. If done correctly, the screen will be distorted (even during the intermission sequences). It will look much in the same manner of when Charles Lee's friend hits Conner over the head and he just wakes up. The screen will remain like this until you are able to pause the game.