HOLLYWOOD — It was a first for the Greek Theater and for Sony Pictures Animation as “Open Season” screened for 3,000 guests Monday night among the towering pines surrounding the Griffith Park venue.No expense was spared for the inaugural premiere of Sony’s 4-year-old animation division, and everyone involved actually showed up for the pre-party in the parking lot. Yair Landau, prexy of Sony Pictures Digital, said “Open Season” was chosen as the first project because it’s a universal story about a mother letting go. He said the division aims to select projects that show the enormous range within the animation sector. Filmmakers Roger Allers, Jill Culton, Tony Stacchi and Michelle Murdocca said the pressure is off now that their film is completed. “This is the first time we will see all the moving parts together,” said helmer Allers, while admitting he probably would be watching the audience for reactions more than watching the film. Helmer Culton said voice thesps Martin Lawrence and Ashton Kutcher took plenty of liberties with the written script, ad-libbing many of the scenes. “They really brought their own personal quirks to the screen,” she said. Paul Westerberg performed three songs before the screening attended by Debra Messing, Gary Sinise, Jon Favreau, Billy Connolly, Patrick Warburton, Demi Moore with Tallulah Belle Willis, Lauren Holly and Sony’s Howard Stringer, Amy Pascal and Jeff Blake.