This is truly a disgrace. It makes my blood boil.
Whenever I am in a race which I've never run before, I am worried about going the wrong way or having to turn around. I did that once at a half marathon a couple of years when the course monitor at mile 12 simply decided to up and leave and we back-of-the-packers were left to guess the direction of the final mile. I missed the turn and added an additional mile to my race. When you're miles into a race, it's really hard to think and pay attention even when you've studied the course ahead of time.
Some race organizers do a great job and others do a not so great job. At mile 25 of a marathon, my brain is operating on par with a lemming. In Atlanta, the course was not adequately marked at the point of misdirection. You need to go back to where you lost the route and go from there. Folks, you shouldn't have to memorize a course. Courses should be marked properly.
Clearly race management was responsible for the problem. I am going to file a complaint with the race director on behalf of the runners who were misled by the pace car. I personally think it's the height of irresponsibility for a road race in a major U.S. city to be so poorly marked that runners get lost. Running is hard enough without these kinds of issues.