Why is the kid not home?
Was the kid just visiting with his grandmother, or was he staying with his grandmother because of the wife seeing the trespasser?
Also, the wife says something to her mom along the lines of, "I can't be sure of what I saw." I'm not quite sure I understand that, either she saw someone trespassing or she didn't. Perhaps I'm reading too much into it?
Other than that, I thought this movie was refreshingly different in it's approach to home invasion. The look of the film was clean and well done.
~ I would like to encourage everyone to watch "Curse 2: The Bite." It's made of awesomeness.