Until senseless real-life violence intruded, anyway, in the form of last summer's Aurora, Colo., movie theater massacre. That event bore a shocking resemblance to an ambush scene set in Grauman's Chinese in the already-made movie. "Gangster Squad's" release was delayed from fall 2012 to Friday, Jan. 11, so a replacement sequence could be filmed and inserted.
More on that later. But first, some thoughts on re-creating 1949 Los Angeles (the entire film was shot locally), when a group of LAPD cops went undercover to bust up the operation of mob lord Mickey Cohen by any means necessary, at least according to this somewhat fictionalized movie.
"I met one guy from the actual Gangster Squad, who was in his 80s," explains Brolin, who plays the film squad's leader John O'Mara. "To be able to talk with him, I think, was more informative than anything because he was a tough guy and he was very stoic and elusive - which I loved - and I found him very intimidating. I think I got more out of that, just the integrity of who they were or what they felt like they were doing, than anything.
"True, they were doing the right thing, but they did it in a way that didn't necessarily follow all the rules," Brolin says. "The fact that 50 years later, he wouldn't tell me anything, I thought, was so bizarre. Like, who's going to care now? But I'd ask him a question and he'd just look away.
Adapted from acclaimed journalist Paul Lieberman's nonfiction book of the same name, "Gangster Squad" depicts how Cohen, played by a fire-breathing Penn, came close to making L.A. the hub of all mob activity west of Chicago. He wasn't brought down the way the movie shows it, but he was stopped, forever preventing the mafia from establishing a foothold in town.
Sgt. O'Mara existed, too, but the square-jawed, square-shooting war veteran Brolin plays is not a historical replica.
"I got a lot of information about John O'Mara - I got a lot from the daughter," says Brolin ("No Country for Old Men," "W."). "I wanted to be respectful to the family in representing their father well, but I also let them know that it wasn't their father and that it's going to be different. It is a composite character."
Stone had different images to live up to as Grace Faraday, an aspiring actress and Cohen's moll-of-the-moment who finds herself dangerously attracted to Gangster Squad member Jerry Wooters (Gosling). Grace's cascading red hair and slit-up-to-Alaska evening gowns were clearly influenced by '40s screen siren Rita Hayworth, while her naturally low, smoky voice evokes that of ultimate film noir dame Lauren Bacall.
Stone, 24, credits production professionals with making her look the retro-glam part.
"Mary Zophres, the costume designer who was really amazing, and her team built me, like, a plaster bust that they could put over my real, straight up-and-down body, so I could look like a lady in the 1940s," Stone says with a grin - and not the one you'll see onscreen, either.
"I had fake front teeth for a little more of a '40s movie star smile instead of my, um, smile," she says. "The hair was mostly mine, with some pieces in there, too."
One thing Stone was glad she didn't have to do, though, was follow the trajectory of the typical film noir femme fatale from movies of the period.
"I don't think Grace is pure, by any means," acknowledges Stone ("The Help," "The Amazing Spider-Man"). "Her involvement with Mickey is self-serving. But there's none of that cold twist of vengeance in her, so that was nice. She's not a stereotype."
The movie doesn't need any of that for excitement, considering all the brutal fights, punishing torture and ballistics it serves up. The filmmakers make no apologies for "Gangster Squad's" copious gun violence. But Fleischer did admit at a press conference - held the day after the Newtown, Conn., elementary school shootings in December - that following the Aurora massacre, "Gangster Squad's" theater shootout had to go.
"The Aurora shooting was an unspeakable tragedy and out of respect for the families of the victims we felt it necessary to reshoot that sequence," the director said. "I'm proud of the fact that we did that, and we didn't compromise the film or intent.
"I think that we should all respect the tragedy and not draw associations to our film as a result of any of these types of tragedies."
Like that can be helped. Brolin still seems stunned by how closely real life resembled the staged violence.
"With this, it was so similar that it was like, OK, this is beyond being disrespectful to the families, this is just f-ing weird," Brolin says.
Even though some cast members weren't thrilled about fitting the replacement shots into their busy schedules, Brolin feels that the new sequence, set outside in Chinatown, is an aesthetic as well as an ethical improvement.
"I actually like it better, and the fact that we came back and did it, there was something a little more organic about it because it wasn't pushed," Brolin observes. "There's something good about when you kind of don't want to be there. You stop acting so much and you just are, and sometimes that can be better. I find that scene to be more authentic than most in the movie. It's not pushed; when you see me furrow my brow, it's real, it's not fake."
Filming L.A. history all over Southern California was, ultimately, the great takeaway for Brolin. A seventh-generation Californian born in the city, he even got his actor father, James, to tell him stories of trying to sneak into Slapsy Maxie's, the nightclub where Cohen hung out, when he was young.
"The whole homage to Los Angeles is a huge thing for me," Brolin says. "Once I became an adult in my late teens, early 20s, I was ashamed of being from California because I wanted to be an actor and I thought valid actors were only from New York and all this. I was really ashamed! I didn't want to tell anybody.
"So I've gone completely 180 because I'm so ashamed of myself because I was ashamed! But now I'm back, for years now, and a true, very prideful Californian. I love this place, I really do. So, yeah, it was a nice opportunity for me to pay homage to a place that I love."