San Francisco's Union Square is definitely a public space to visit. If you're not paranoid about being bugged, you know, like in Francis Ford Coppola's iconic "Conversation".
The other great park in SanFran is Mission Dolores Park, featured in Clint Eastwood's iconic "Dirty Harry". But it's more pleasant to visit during the day light.
"Dirty Harry"'s Aquatic Park is a historic landmark of the city that has a lot of things to see (like San Francisco Maritime Museum) and you can feel yourself like Clint Eastwood here.
Wanna see a huge cross in the middle of the park from "Dirty Harry"? It's on the Mount Davidson. The concrete cross is the site of a yearly prayer service, performed on Easter.
Have a walk a long the Pacific, like Gigner and Al from Woody Allen's "Blue Jasmine". It does worth even if you're not very much into that film.
You can't have a San Francisco Movie Trip without Golden Gate Bridge. And if you go there and see a traffic jam, it might be a riot of... apes. Well, rise of their planet... Whatever, apes!
...If you get on the bridge, you still may stuck there because of the attack of Godzilla.
...or a monstrous kaiju from "Pacific Rim".
If you're finally out from the Golden Gate, go back and have some rest in Portsmouth Square Plaza.
Or just have a rest on a bench on South Park street. But we hope you're more happy than Cate Blanchett's Jasmine in this scene. Well, you're in San Francisco, just be happy!