This bonus isn't hard, either. You have to get through the frenzy of people to get to Marion, Mutt and Oxley. Then, you must escape the church, get in a car, and drive off. This will start a chase with some surviving Russians chasing you. When you get to Indy's house (arrows are guiding you,) the level is done, Unfortunately, Indy's house is a long way from the church.