410 got restarted in my bag after my race...

First of all, congrats on your marathon! :D Leaving the device running happens more than you think. There are a couple of tools you can use. After exporting the TCX file, you can edit the file with an xml editor, such as firstobject XML editor. Use that to edit out the errant tracks. The trick is finding the exact track where you need to start deleting. To find it, I like to use TCX Converter. Find the exact endpoint of your marathon and make a note of the trackpoint time. Then with the editor search for that time. Delete every trackpoint after it. Then you'll have to calculate the exact time in seconds and distance in meters of the last lap. I did my best, not knowing the exact end of your marathon, but looking at your track and comparing it to other runners that had uploaded to GC. It looks like trackpoint "2012-04-14T15:36:34.000Z" is where it should end. I've attached the fixed tcx file here. You can upload it to GC or try the tools mentioned above to create you own TCX file.