Near the end of the movie when Dusting Hoffman is driving south from San Francisco, he drives through the Gaviota Tunnel. The Gaviota Tunnel is on the northbound lanes of the US 101 Freeway.

Also, he exits the car near Ellwood and then runs/jogs to a church in Montecito. The distance is closer to 20 miles in reality. He would have missed the wedding for sure.