In the diner scene near the beginning of the movie, Charlotte is not wearing a necklace. When she drops Evan off at his apartment after their rendezvous, she is wearing a large pearl necklace.
When Shirley drops Evan home they talk a bit and we can see Evan wearing the safety belt, then we see Shirley, then Evan again but without the safety belt on. At the end of the conversation we see Evan with the safety belt on.
While driving on the freeway with Evan, Charlotte has her hands on the steering wheel which is at a 90 degree turn to the left. She would not be going straight with the wheel like that. You can see that her hands are placed correctly, but with the wheel like that, they would be driving in a circle.
When Evan is typing his password at the Last Word's web-page, the hits on the keys we can hear are too many for the characters of the password (they are six and we can hear at least ten hits).
At the 32 minute mark, Charlotte says that 5% of one half of 4000 is 150, then says, "I'm good with numbers." The correct answer is 100.