Have you ever run a course where it seems like there is NO WAY it's only a 5k?. You run out of gas after what you think is the fourth kilometer. You don't want to check your tracker, but you do. Wait, there's MORE? Is the GPS off? Did it not start on time? All these things run through your head, but surely the event organizers did the proper math. Right?

Not always:

According to the Associated Press, some runners of the Maine Coast Marathon were mistakenly directed down a dead end before looping back, bringing their total distance to about 26.7 miles. The standard being 26.2. The error caused some Boston hopefuls to post times that are unlikely to qualify.