The guy who had to edit all that raw footage is one lucky bastard, wardrobe malfunctions, are common in these kinds of ads, especially with someone like Sydney who likes to show skin so she doesn't mind that much. I think there’s a nip slip in the Charli XCX thread where she’s on set filming something, it’s always more likely to happen when the model is a woman like Charli or Sydney, they like to show skin.
I bet there’s raw footage where you can see Sydney’s asshole, when she leans over the angle changes in the edited version, but those cameras keep recording.