The rules of the trail are many. Wrangler Shawn explains how important it is to follow the rules. One of the key rules is that, since mules are herd animals, they do best if following each other closely. He hands out whips (crops) to each rider and they are told that this "motivator" is necessary to keep the mules in line and close together.
He also explains how the mules are trained to walk on the outside of the trail and when stopping are trained to face out, toward the canyon. The reason for this is that if a mule is spooked by something unexpected, they tend to back up. Now we wouldn't want them to back up toward the canyon would we?