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: Silva's objective was not just to kill M - if it was, he could have blown up her office with her in it when he hacked into MI6 the first time. He wanted to humiliate and terrify her by showing he could get to her again and again, whatever measures were put in place to protect her.
Sierra1 ★