Margot Robbie chats with ET's Kevin Frazier in Los Angeles at the premiere of 'Babylon.' The actress jokes about the 'Barbie' trailer leaking online the day before its official release. Margot also shares her excitement for Lady Gaga playing Harley Quinn in 'Joker: Folie á Deux.' Plus, she breaks down her Old Hollywood-inspired red carpet ensemble. 'Babylon' hits theaters Dec. 23.
