These are good things to know. I've had 3 bad experiences with Harley over the last 5 days or so..
The first time, we were doing our off the leash time alone in a large school field, when someone else showed up with her dog still on a leash, Harley took off running. I yelled "stop" and "come" (I'll have to admit, I don't have any training class experience, Jakey was naturally a good boy and I never had an issue training him in "my own way".) Anyway, Harley ran and ran and then I ran and ran, I was chasing him around this lady and her dog trying to get his halti back on him, until she finally let her dog off it's leash and they played. The next time, it was the same type of thing.. we came out of the woods, and far across the field was a man throwing the frisbee for his dog. Needless to say, there goes Harley, and then there I went. The final day, we were still in the woods, and WAY across the field - not even in the field was a man walking his dog on the sidewalk. They were so far away, that I couldn't even see he had a dog with him. Harley took off like a shot and would not listen to me. I could've started screaming like I was on fire and he wouldn't have turned around. I finally arrived, and I could see the man was angry, his dog apparently was not a nice dog, and he was trying to keep them separated. Again I had to chase Harley around the man and finally got him. I was soooo angry at him, I took him straight home and cried - I felt terrible for the rest of the night. I know it's my fault for not learning my lesson by that point - I have now... For the 5 months that we had been out for our off the leash time he had never done this - and we go out almost every day.