Recently, in Bangkok, a bunch of runners gotten a little more than they bargained for when they set out to do a half marathon as part of the Bangkok Marathon. The race organizers appear to have added 6.5 kilometers or 4 miles, to the end of the race. It looks to be an honest mistake with a gate being left open. People headed the wrong direction when they were doing the course making it the world's longest 'half-marathon.' It does look like some people, pardon the pun, took it in stride, while others when done, and finding about the additional distance were worried about their health. I've been in quite a few races, not just in New England, where you felt like even before you crossed the starting line you knew the organizers didn't know their course. Most often in my experience it's usually cut off distance with a 5 kilometer course turned into 3 miles. It cuts off about 0.1 of a mile which will only cut off maybe 1-2 minutes for the average person but isn't really a big deal for most people. The issue is if your race is at all choreographed, it messes with your rhythm and with the time you were trying to run. It isn't easy to add distance, but most often I feel like it can really surprise people of their own capability.
I'm not a huge fan of funky distances, but it is better to be warned beforehand, like the Dreamfar 10k - 2015 I did at the beginning of this year. The course looped around Lake Massapoag in Sharon, MA and it was one of the more scenic courses I've ever done. With the lake on one side and the snow and ice on the trees on the other, it had a stark beauty I've rarely experienced; it was like running though a serene black and white photograph. Most of the course we did was flat, so what little ice was on the road didn't really matter... until we got close to a fairly steep hill. The organizers were rightly worried about the competition accidentally entering a skiing stage. It ended up being closer to 5 miles than the 6.2 miles we originally set out to do. It was cold and I was happy to be back inside quicker than expected plus, it was only a mile. On race day funky distances are pain, but taking the long view, I feel like they usually play out in your favor; it would be cool to have been in the world's longest half marathon.