Continuity mistake: We see Nina put on red lipstick on the subway. In the next scene, when she's in the studio, her lips are skin-colored, implying that the lipstick is off. But when she enters the director's office, the lipstick is on again, even though she never reapplied it.
Continuity mistake: When Nina watches Lily dancing after filling up her water bottle, look very closely at Lily's back as she spins around and you can see that her tattoo isn't there. As she was wearing a vest and her hair was down over her back, it is likely the film makers thought they could get away with this.Liam D