Peterson Car Museum
After you experience the Fast and the Furious at Universal Studios you can head to the Peterson Car Museum to see the cars in real life. They even have an exhibit celebrating 25 years of the Fast & Furious franchise. The museum is about an hour away from Walnut.
If you’re up for a museum day you can also hit Los Angeles County Museum of Art which is just down the street and then have lunch in Koreatown.