The Darjeeling Limited

On a train in India, called "The Darjeeling Limited", Peter Whitman (Adrien Brody) reunites with brothers Francis (Owen Wilson) and Jack (Jason Schwartzman). The three have not seen each other since their father's funeral a year prior, and having recently survived a near-fatal motorcycle accident, Francis wishes to reconnect with his brothers on a journey of spiritual self-discovery. The three continue to grieve over their father's death, carrying with them a large set of luggage marked with his initials, along with other personal items of his.
The train takes the brothers through the countryside and en route they visit towns and Hindu temples. Animosity builds as Jack and Peter become annoyed with Francis' controlling behavior, and Jack has a romantic encounter with the train's stewardess, Rita (Amara Karan). Francis eventually reveals that they will be meeting with their mother (Anjelica Huston), who has become a nun living in a Christian convent in the Himalayas. The brothers' bad behavior on the train causes the Chief Steward (Waris Ahluwalia) to have them thrown off. At the same time they receive a letter from their mother suggesting she does not wish to see them, and decide to return to the United States.
While traveling through the countryside, the brothers attempt to save three young boys from drowning in a river, and succeed in saving two, with Peter's child being dashed against rocks. They carry his body back to the boys' village, where they spend the night and are warmly treated. They attend the funeral the next day, and a flashback sequence shows events that took place when the three brothers were en route to their father's funeral.
The brothers are on the way to the funeral when they learn that their mother won't be attending. They stop at an auto shop to retrieve their father's car and drive it to the funeral. The mechanic tells them that the car is not running yet, but they start it anyways and drive into the street, nearly colliding with a tow truck. The tow truck driver confronts them, and the brothers threaten him until he leaves.
The brothers arrive at an airport but change their mind about leaving just before boarding the plane. They travel to the convent and meet their mother. During the night, the brothers confront their mother for abandoning them. The next morning, they awake to find their mother gone.
Traveling to a railway station to catch another train, the brothers arrive after it has begun to depart. Chasing it, they realize they will be unable to catch it weighed down with their father's suitcases. The brothers fling their baggage away and jump onto the back of the train.
Hotel Chevalier[edit]
Main article: Hotel Chevalier
Anderson also wrote and directed the 2007 short film Hotel Chevalier, starring Jason Schwartzman and Natalie Portman. The 13-minute film acts as a prologue to The Darjeeling Limited. In it, Jack's ex-girlfriend (Natalie Portman) turns up unexpectedly at his hotel room in Paris, and they spend the night together. Originally attached to festival screenings of The Darjeeling Limited, it was removed during the limited theatrical release and instead made available on Apple Inc.'s iTunes Store as a free download. On October 26, 2007, Hotel Chevalier was removed from iTunes in favor of releasing it in theaters with the wide release of The Darjeeling Limited.

Question: What causes the Chief Steward to throw the brothers off the train?
Answer: Bad behavior