i dont remember seeing any type of close ups on mike that show him ducking, i remember seeing shots, and a full shot of everyone on the stairs, but i may be wrong..............but as far as mary being the target your theories are starting to make me feel otherwise, i was getting different interpretations while watching. it was just hard to believe that this "ace in the hole" assassin standing 15-20 feet away only hits michael once and in the arm.

In my home! In my bedroom, where my wife sleeps! Where my children come and play with their toys. In my home.