The 29-year-old actress stepped out in a white blouse which gaped open to reveal much more than she planned, reported E! online.
Besides Barton, Martin Sheen also attended the event. "Bhopal: A Prayer for Rain" is a history drama that travels back to 1984 when the Bhopal gas tragedy occurred in India.
The film explores the interwoven stories of people in both India and the United States in the months leading up to one of the world's biggest industrial disasters.