I haven't signed up for this yet but I will in the next day or two. Here's the course map for the Mission Inn Run.
The race starts on a major street near the Mission Inn. I guess the Mission Inn itself isn't part of the race. Anyway, it loops down toward the 60 Freeway, around Fairmount Park and back towards Market Street.
Of course, this means absolutely nothing to you if you've never been to Riverside.
However, the course seems pretty simple and straightforward. I have to admit, I don't like having to run the same course twice. I'd much rather run one long 10 kilometer stretch. But at least it's an option. I don't think I'd enjoy the 5K as much as I'll enjoy the 10K.