The walkway you're standing on may not be exactly the same one Orson and Rita stood on in The Lady from Shanghai, but it is in exactly the same spot.
Valhalla, behind you, was there at the time the movie was shot and can even be seen in the movie. It's the big restaurant full of witnesses when Welles fires the fateful gunshot at the pier. You may also notice that many of the houses and buildings are the same, give or take a coat of paint or a new skylight. Try printing the pictures for the cache and bringing them with you. It's fun!
Extra points awarded if you can show a photo of yourself standing in the same place where Rita and Orson are in the photo above! (There is a bigger version of it in the list of photos below.)
The cache itself is rather small. You can bring something coin-sized to trade with, or just sign the log book.