Anna's car has a 7-digit California license plate in the 1AAA111 format. The movie is set in 1973 but this format was not used until 1980. Cars in California in 1973 had 6-digit plates in the 111AAA format.
The movie is set in 1973 when the fashion for men was to have long hair and sideburns. None of the male characters have sideburns and Sean Patrick Thomas has a fade haircut which wouldn't become fashionable until 20 years later.