Revealing mistake: When the train plummets into the basement, the windows never seem to smash nor crack, nor does the paint on the train ever seem to scratch the slightest bit. (01:34:15)
Revealing mistake: During the motorbike chase, after a man says "they're on the rooftop of the grand bazaar" Bond's bike jumps and right after there's a wide shot where the driver is not Daniel Craig but a stuntman.
Answer: Because Bond is fighting to the death with a man who's trying to throw him off a train. He can't exactly step out of the way.
Brian Katcher