The French beauty admits she isn't usually one to spend hours in the wardrobe department on the set of her film projects, but this time was different as she fell in love with the period clothing.

"It was the first time I would like, run to costume fittings," she smiled on U.S. breakfast show Today.

Director Robert Zemeckis recruited his frequent collaborator, costume designer Joanna Johnston, to work on the World War Two film's fashions, and she turned to old photos and films from the '40s to help her capture the glamour of the era onscreen.

Among her movie inspirations were the onscreen ensembles worn by the likes of Lauren Bacall, Bette Davis, and Katharine Hepburn, while she also paid close attention to the outfits worn in the Humphrey Bogart and Ingrid Bergman classic Casablanca, partly because of the shared setting, since part of Allied is also set in Morocco.

"We created everything for the film to give it that lift, and to give it that kinda gloss," Joanna explained. "It's like a definition."

And her hard work paid off as Marion loved playing dress up in her movie wardrobe.

"Everything was beautiful: the hat, glasses, shoes, gloves...," the actress gushed, "so I was like a little girl playing doll (sic) with myself."

Marion stars alongside Brad Pitt in Allied, about two assassins who fall in love during a mission to kill a German official.

The movie is released in theatres from Wednesday (23Nov16).