As someone who is involved with the chariots this year and was actually in the race when this accident happened maybe I can help.
The chariot that was involved was sitting on a straight axel. It was up really high off the ground and made it really top heavy. They said it was built by a master craftsmen but IMO was not well thought out. The chariots that you mostly see have the normal drop axel, where as the body of the chariot is like in a cradle per say and close to the ground. Another thing is he was also in a box not just a bar in front like many chariots have but also had a configuration to where he had something behind him as well. Also he was tied in, I heard mix responses that he was strapped in or show management told that he couldn't go in being strapped etc...
We were all saying it was an accident waiting to happen and unfortuantly it did. You can see pics of the chariots at casey mcbride photography and you can see the difference, even more so in person. They are saying now that the rules will be changed to you must have a dropped axel and you cannot confine yourself into the chariot. Possibly be brought up at Convention. He was cut pretty badly but he made it, it could have been a lot worse as not only did he flipped but dragged a few feet because he could not get out of the box he was in.