The original ending had Denis Leary being caught by the cops to show the son that a life of crime leads nowhere. However, after screening the movie to a test audience and receiving negative comments about the ending, director Ted Demme changed it. He now admits he regrets changing it.
This film takes place in Connecticut. Several characters mention a county prosecutor throughout the film. Connecticut dissolved all county-level governments in 1960 and thus, there would be no such thing as a county prosecutor. In Connecticut, counties are solely geographic entities.
When Gus is in the car with Lloyd and Caroline and Lloyd runs a stop sign, Caroline is clearly not wearing a seat belt as she looks behind the car. Once the three are facing forward again, the seat belt is magically across her chest.