Marshall loves authenticity, so the film crew spent last December 31 in the middle of the Times Square madness.
"We shot 2011 the actual New Year's Eve, 15 cameras. I say that proudly because I didn't shoot it, my son Scott shoots the second unit," said Marshall. "They had all these different cameras and they were shooting, and then ... we brought in thousands of extras and assimilated it."
But just before filming, the Marshall crew realized it was facing one big problem with the revelers.
"They're waving things that say 2011," laughed Marshall. "So it was a rush to get 500 hats and banners that said 2012. And we went to strangers and said, 'Will you put this on? You can be in a movie.'"
"New Year's Eve" opens in theatres Friday, Dec. 9.