Continuity mistake: The fence at the start of the movie changes as Cujo chases the rabbit. In the shot as they run towards it, there is just one straight plank running across the bottom. When they reach it, there is now an askew, diagonal plank attached to the straight one. (00:02:00)
Continuity mistake: After shutting his closet door, Tad runs over to his lightswitch. In this shot the lamp on the desk, beside the lightswitch, is standing high up. In the next closeup of Tad reaching the switch, the lamp is in a different position, then switches back. (00:04:25)
Answer: Not really. Rabies has a wide range of behavioural symptoms, and it's rare for a rabid dog to display what's called "furious rabies," whereby they become more aggressive. And even then, they wouldn't become single-mindedly determined to terrorise two people in a car. It's much more common for a rabid dog to get slower/lethargic as paralysis sets in, eventually leading to coma and death. You can find more info here: https://vcahospitals.com/know-your-pet/rabies-in-dogs.