Corrected entry: Warning: This next mistake contains a spoiler so if any of you haven't seen the film, please don't ruin it for yourselves: Nearing the end of the film, Naomi Watts' neighbor comes to pick up her stuff and says: "These 2 guys were looking for you AGAIN". A second later, Naomi sees the key on the table. If the key is supposed to confirm the assassination took place, and she notices it only then for the first time, why were these 2 people looking for her? The assassination hasn't taken place yet.
Corrected entry: In the studio while listening to the singers, the director has his headphones on. we can see the wire running down from them. Then he stands up and walks towards the actors or whoever, and there's no wire at all. When he returns, the wire appears again.
Correction: As he walks back to his chair, you can clearly see that the wire of his headphone is connected to a receiver from a wireless system, which is attached to his belt. Even when he walks up to the singer, we can still see the wire of his headphone.
Correction: There is no reason to believe that this was the first time she saw the key.