No, not an error. Regular 1984 quarter- just $0.25. Circulation damage, like paddyman said, or scratched along the pavement.
Welcome to the forum Kim. You can learn a lot about coins on CT. There are some very knowledgeable people here.
Keep looking Kim. You spotted this one you might find a good one next time. Just post and ask as you did this time. Some nice folks here will help you.