"Witt smokes in about 4 scenes, the last towards the end of the movie when she passes a cigarette to Jena Malone who tales one drag then coughs."
Other references to this movie:
Mila Kunis - Proof - no - Mila herself states that she doesn't smoke IRL, She faked it for the film in the one and only scene where she's shown smoking, American Psycho II: All American Girl (2002) DVD
, Allposters.com