Hilary Swank kept "cursing" while filming New Year's Eve, says director Garry Marshall.

The star is one of many big names in the new movie, which follows several intertwining stories all taking place on December 31 in New York.

The huge ensemble cast includes Robert De Niro, Michelle Pfeiffer, Jessica Biel, Zac Efron, Sarah Jessica Parker, Jon Bon Jovi, Halle Berry and Ashton Kutcher.

Garry was delighted to work with so many big names, but was pleased each one was only on set for a short time.

"We got these stars because, except me, nobody was there over five days. Egos don't act up in only a short time," he told the New York Post. "Swank, wanting to do comedy, got the giggles. We had to beep her cursing. Biel wanted to film a pregnant girl. Ashton looked to stay indoors. Up on the roof with the real New Year's Eve Ball, filming at 2.30am, Bon Jovi said, Concerts don't go this way. Concerts stop at midnight.'"

However, the director said the main difficulty with filming was coping with the freezing temperatures.

The 77-year-old had a unique way to keep warm.

"Four months I was in New York filming this. Last December 31 I stayed in my warm hotel room while our second unit filmed out in freezing cold," he laughed. "I'm a Bronx kid who lives in California because it's chilly here. I'm old. They built a tent to keep me warm. Problem is, in five minutes the damn wind blew the whole thing down. But I found how to survive. I said, Let's go into the bar.'