Audio problem: Halsey tries to get the family in the station wagon's attention by honking his horn. After the near-collision with the bus, the horn honks in a different note.
Factual error: All the police officers are described on the cast as 'troopers', but those who arrest Jim at the diner and those who pull him off the bus are actually deputy sheriffs, not state troopers. They are not wearing uniform, are not driving cars with state police badges, are wearing stars instead of police shields, the place where he is taken after being arrested has 'Sheriff Station No.7' written on the outside wall, and the name of the sheriff's department can be seen when he is being photographed.
Continuity mistake: C. Thomas Howell has a mole-like thing on the left side of his chin, that appears, disappears, and fades between shots.
Continuity mistake: When C. Thomas Howell is looking in the mirror, in the shots taken from above the mirror, it is not that dirty. Yet, when it cuts to a close up of the mirror, it is filthy.
Answer: The windshield glass would have not broken this easily (like regular window pane glass in your home or such). I am going to guess that kind of glass hasn't been used on car windshields since at least the early 70's, if not before. The Sheriff's truck didn't appear to be that old, either.