Revealing mistakes: At the party Vincent Cassel gives his characters name as "Vincent" instead of "Marcus" He quickly covers his mistake.
Continuity: When Alex walks down the stairs of the tunnel, the knot of her dress around her neck and her hairstyle change after the camera shows the sign "passage" and comes back to Alex's back.
Crew or equipment visible: In the scene where Monica is in the bed with her boyfriend and they get up to dance, the whole film crew is mirrored on the glass of the window.