Continuity mistake: When the phone begins to ring, Cujo goes mad and starts bashing the side of the car in. He then shatters the passenger window of the car. In the very next shot it can be seen intact again and then alternates from shattered to intact from thereon. (01:01:15)
Visible crew/equipment: When Vic is at the elevator, about to leave the hotel, and Roger is talking to him, one or two crew members are reflected in the picture hanging on the wall next to the elevator. (01:08:50)
Continuity mistake: When Donna takes Tad into the house, she pushes some items off of the table, and lays Tad down on the table. In following shots, items around the floor and on the table change position. Most noticeably is the milk carton beside Tad's head. (01:23:30)
Visible crew/equipment: When Cujo gets into the vehicle and is fighting with the woman, we see a shot behind the dog. The shadows of a boom mic and film equipment are blatantly visible.
Factual error: The car is equipped with shatter-resistant glass yet Cujo manages to break through - even rabid, this should not be possible.
Visible crew/equipment: As the car is breaking down a second time, the camera is moving around the driver's side. It is visible in the glass, bottom left.
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.