Around 58 km in going through some muddy areas something happened to my derailer that caused it to explode, and bend in on itself and into my spokes and gears (see picture). I walked the last 2 km after bending the derailer out of the spokes. Wes and Maygan were waiting for me at the finish line, and Wes ended up pushing me across, which should be in some photos somewhere online. I'll have a look for them.
All in all a good race, though my time wasn't great, and wouldn't have been great even if I didn't blow the derailer. I need to get in better biking shape.