Are there things to do outside comic con.?

Heck yeah... here's a guide to some of the more popular ones and each has a section on nearby things to do: http://www.vacationrentals.com/destination-guides/...

I didn't get tickets but I was wondering if it was still worth going to, if they had anything going on outside the convention center that was worth dressing up and going to

It depends on the Comic Con you're going to, but 99% of the time there won't be anything to do aside from walk around and take pictures of other people. All official Comic Con events are held inside, though fans might get together and hold a cosplay photoshoot or younger attendees might play con games (like Ninja and Ride That Mustang) if the weather's decent.