That is hilarious. I'm glad I'm not the only runner who thinks about that. My friend and I joke that a Race Director has 2 options: either make the course 3.1 miles and have the finish line be in some bushes, or make it 3.0 miles and have it be right in the center of a parking lot.
I once e-mailed a Race Director before a race to see if the course was certified and she replied that accuracy wasn't important because it was only a "fun run".
There is another race in the Columbus, OH area that runs a 5K loop-course. Well, one year they decided to change the direction of the race (run the loop backwards). But they left the mile markers in the same spots. So the first mile marker was actually at 1.1 miles. Everyone thought they were running unusually slow at the first mile. I didn't figure out what happened until after the race.
I'm a bit disappointed in the 5K this past weekend, because it had over 1500 runners. I think a race that size deserves an accurate course. It didn't even have a Two-Mile marker.