The kid in the car
First off, I loved this movie. But of all the bad things that happened in the movie, the one this that drove me crazy was the kid standing, walking around, and jumping in a speeding car. Nothing gets me more riled up in real life than seeing a kid not buckled up or sitting in someone's lap in a car, but seeing a kid hopping over seats in a covertable had me yelling at the screen. I know it was just a movie, but it bugged me.
But it is an awesome movie.