Henry S. Dziekan III, WireImage

Michelle Williams' co-star Zoe Kazan revealed some unique wardrobe benefits enjoyed by the female cast of "Meek's Cutoff," at a screening Monday night in New York hosted by the Cinema Society and accessories designer Nancy Gonzalez.

Kazan explained her favorite features about their 1845-style dresses with full skirts: "You can wear no underpants and just squat and pee and that's really useful. You can do it in public and no one will see you. You go out into the fields and cop a squat under your skirt. It's true that's what the pioneer women used to do."

Williams confirmed to StyleList that she also went commando during filming in the Oregon desert. "It's true. That's one of the things I missed about those dresses."

The actress detailed why she enjoyed her atypical bathroom breaks. "Well because it's something that's a luxury that only ever afforded to a man so I relished in that for a moment."

Williams' period costumes were historically accurate because the sewing machine hadn't been invented in 1845. She pointed out, "Every costume in the movie was sewn by hand completely."

The narrow bonnets and long hemlines were initially quite challenging. Williams said, "At first very strange, and it felt like an ordeal to learn how to move in them and move in them comfortably but after a while, both Zoe and I came to miss them."

Would the 30-year-old consider incorporating pioneer style into her current wardrobe? "We talked about it once the movie was over -- if we could bring back prairie skirts or rock a bonnet. But so far, I haven't seen either of us doing that."

Williams, clad in a decidedly more modern Chanel shift dress, revealed, "I've never worn a sequined sleeve before." She accessorized with a large cocktail ring from the same design house and explained what she adored about the French brand, "It's effortless." Understated Ferragamo pumps completed the sleek European look.

The pixie-haired beauty explained her instinctive red-carpet philosophy: "Don't you kind of know immediately when you put something on whether or not you feel good? That's all I really go by."

Guests enjoyed an after-party at Jimmy at the nearby James Hotel, lubricated by Appleton Estate cocktails.