For the star studded premiere of the film, Rachel wore a show stopper Marchesa Fall 2011 red organza gown with ansheer long train with ruffled red edges and illusion cap sleeves.
She matched her sartorial splendor with dramatic hair makeover - honey blond color with platinum highlights. She rounded her perfect seductress look with side swept retro waves.
Earlier in the day, the 32-year-old Canadian actress wore a chic white Maxime Simoens frock at the film's photocall. The short sleeve knee length dress had floral embellishments on shoulders and pockets.
She accessorized with towering Salvatore Ferragamo peep toe heels, Bavna earrings, a statement Brumani ring on her right hand ring finger.
Her hair, styled straight and framing her face with a middle parting, was apt for the outdoor morning presser.
She was accompanied to the event by costars Adrien Brody, Michael Sheen, and Owen Wilson; and director Woody Allen. French first lady Carla Bruny also stars in the film but was a no show at the festival.