Though the Randall Miller-directed drama is about New York City's punk-rock scene and CBGB nightclub, the film -- also starring Malin Akerman, Justin Bartha and Alan Rickman -- was shot in Savannah, Ga.
"My family is in Jacksonville, Fla. and it's only a two hour drive, so every weekend my family would come up and visit me," Greene told Us. "I had friends out there too, so we would just go out in Savannah to little things that were walking distance. The funniest part was that after we wrapped the cast would go and do their own thing, but 90 percent of the time you would run into your castmates in town because the area was so small. It was fun just running into and hanging out."
Her most memorable run-in?
"The best one was running into Johnny Galecki in Savannah because I was with my parents and they're huge Big Bang Theory fans!" she shared. "It was nice to watch them freak out about him. My mom and dad were just geeking out."
Greene hasn't been bumping into her former Twilight costars -- Kristen Stewart, Robert Pattinson, Taylor Lautner, Kellan Lutz, Nikki Reed and others, all of them working around the world -- as much these days, but she tells Us they "all stay in touch as much as we can."
"It's hilarious, because Kellan is always in Bulgaria! I'm like, 'Why are you out there still?' But it's good for him," she explained of the actor working on his next film, Hercules 3D, overseas. "Skype is kind of a way for everyone to stay in touch when we are off filming in different places. I see everyone ever so often, it's nice to play catch up. It's a pro and con that everyone is so busy."
"There was a bond formed by being a part of something as massive as Twilight," Greene admits, "so it's nice to reconnect with all those people when we can."