i think its amazing all this talk over a mirror,that some body probably broke off at some time during production and they just stuck one on so they had a mirror,
in Austin Nevada we ran in to the mayor and he was around for the filming and his dad owned a service station in town and they did some of the work on the cars, he said they beat the crap out of all the cars, and even in the the interview with the director he was worried about there budget since they were crashing cars and raising the cost , so a cheap mirror was probably in order , im sure a replace ment was either not around or to expensive , remember they crashed an old cramero instead of a new chally