When the girls play the Ouija Board game, Andrea says that she wants to contact her Grandma. But later she moves in with her Grandma. However as people have two grandmothers, one could have died, and she moves in with the one that is still living.
When Steve and Brandon pull over in Steve's Corvette in front of the nightclub, you can see a microport on Steve's back while he steps outside of the car, it's visible for almost 3 seconds until his jacket covers it again.
When Kelly talks about her "real" first sexual experience, she says the guy's name was Ross Weber. But later, when they are all in college, she tells them his name is John Sears.
During the Ouija Board game, Andrea asked who's spirit they should contact, and Brenda said that she didn't know anyone who has died. Later on in the same season in "It's Just a Test", we learn that Brenda had an Aunt Sheila who died of breast cancer at 35.