While driving, the car's front seat headrests are missing on the shot from the rear seat, but visible on other shots. And why do you think that is? So we can see the actors, maybe? Not a goof, a necessary part of production.
When Kevin and his friend are getting snacks in the store, bottles of Bundaberg Ginger Beer can be seen on the shelves at approx 0:48. The labels on the bottles would not have been available in 1989 as the current label was launched in 2015.