In late February, when Matthew Perry departed the Dallas set of his and costar Elizabeth Hurley's romantic comedy "Servicing Sara" for a rehab facility in Los Angeles, he boarded a private jet that may still need some airing out, reports PEOPLE's "Insider" column. The "Friends" star, 31, was instructed to chain-smoke and drink lots of coffee on the trip home to help keep him from doing any drugs, says the magazine. (Perry reportedly had been taking a combination of the painkiller Vicodin, methadone, speed and alcohol.) The smoke became so thick in the small aircraft that the pilots had to don oxygen masks and all the passengers, who included others involved in the film, reeked of cigarettes when they deplaned.