David Dobkin Director Owen Wilson John Beckwith Actor Vince Vaughn Jeremy Klein Actor Christopher Walken Treasury Secretary William Cleary Actor Rachel McAdams Claire Cleary Actor Isla Fisher Gloria Cleary Actor Jane Seymour Kathleen Cleary Actor Ellen Albertini Dow Grandma Mary Actor Keir O'Donnell Todd Cleary Actor Bradley Cooper Zack "Sack" Lodge Actor Ron Canada Randolph Actor Henry Gibson Father O'Neil Actor Jennifer Alden Christina Actor Summer Altice Chaz's Girlfriend Actor Betsy Ames Betty Cleary Actor Camille Anderson Jennifer Actor Diora Baird Vivian Actor Jed Bernard Italian Wedding Swing Dancer Actor Ivana Bozilovic Ivana Actor Will Ferrell Chaz Actor Steve Faber Writer Bob Fisher Writer Andrew Panay Producer Peter Abrams Producer Robert L. Levy Producer Cale Boyter Executive Producer Toby Emmerich Executive Producer Richard Brener Executive Producer Guy Riedel Executive Producer Julio Macat Cinematographer Mark Livolsi Film Editing Rolfe Kent Original Music Barry Ray Robison Production Design Kevin Constant Art Director Garrett Lewis Set Decoration Denise Wingate Costume Design Sarah Katzman Casting Lisa Beach Casting