What attracted you to the 1970s as a time period?
In the '70s, they had sirens in LA, and they'd go off. You were supposed to go indoors. They'd have announcements like, "Please don't exercise until after 6pm, and oh, you might not want to let your kids play ball today. There's too much pollution." I remember those days. They cleaned it up. At the same time, if you ever walked down Hollywood Boulevard in 1974, it was nothing but porn everywhere you looked. The two problems that epitomized LA in the '70s, I think, were smog and porn. [We wanted] a plot that embraced them both. In the same way as Chinatown, which shined a light on the '30s, we [wanted to] tell the story the way we want to tell it, but as a plot device, these things work pretty well. They speak to the time period.
So it wasn't out of a love for '70s disco.
Joel Silver has a love affair with Earth, Wind & Fire. Since he was a teenager, he's loved the band. When I asked him why he loved them, he said, "If you see them live, they put on these costumes, they look like wings, and they would dance and they would have trombones and backup singers, and people would spin and dance, and it was the greatest live show. Amazing." Then he said, "You know what? I can get Earth, Wind & Fire, and we'll just re-create the band with actors." At the first screening, Earth, Wind, and Fire starts singing, and the audience claps, which surprised me, but it's great.