They live in a pretty crowded suburb of Southern California (a gun control state). Neighbors never call the police about all the gunfire?
Also the whole premise of the movie is flawed. Why live in fear? Just release the evidence. They never speculated whether or not it would implicate him.
Other than that, a pretty good movie.
I liked this movie a lot. As for the plot holes:
1. Patrick Stewart didn't just start firing guns. I'm pretty sure this has been going on for a while and everyone just puts up with it, or like one neighbor, joins.
2. This bothered me too, but my guess is that it does implicate him as there's no other reason to keep it hidden.
Not really "plot holes":
(SPOILERS)
1) Few people are home during the day. He shot once and her MAC-10 was suppressed.
There would have only been one loud gunshot and it was inside, The neighbors may not have heard them, even if they were home.
2) He does have Alzheimer's. Perhaps he keeps forgetting to release it.
Bad films are a crime against humanity.
Don't forget he did a lot of target shooting outside and pest control in the yard. Someone had to hear it.
share<Here there be spoilers>
My feeling was that it was his insurance policy. He knew too much about too many things. "They" want him dead, but as long as he has this info, and doesn't release it, they leave him alone. At least in theory. If he lets the cat out of the bag, then there's nothing to stop them from killing him. Hence the reason for the whole "dead man" computer program, that requires him to input his "password"(in the form of solving the graphic puzzle) at random intervals. If he's not alive to stop the program, the info gets released. Presumably "they" know this fact.
And to answer the next question that I see coming: "Well, if he releases the info, then there's no reason to kill him anymore, right?"
Well, no. Again, the assumption is that he knows about a great deal of things, not just this one thing, that's why they want him dead. This particular thing is the only one where he has extensive documentation that can harm them, hence it's his one and only insurance policy. Once he spends, or looses, that card, he's SOL.