Colin Farrell doesn't come across as a gullible type, but the Irish actor was terrified when partaking in a fake drug deal as part of his preparation for Miami Vice. The 2006 Michael Mann film starred Farrell and Jamie Foxx and was based on the popular TV series of the same name that ran for five seasons in the '80s. The duo played Sonny Crockett and Ricardo Tubbs, the same roles made famous on TV by Don Johnson and Philip Michael Thomas.
The film version of Miami Vice emulated the overall look and style of the cop show, which often featured drug-themes and was known for its trendy fashions, flashy cars, exotic speedboats, and sultry environments. Michael Mann, who wrote and directed the movie was also a producer for the TV series, so it's no wonder it preserved a lot of the show's appeal. Mann also made sure Farrell was well prepared for his role as a detective going deep undercover in order to take down a Colombian drug cartel.
Part of the research Farrell did for the Miami Vice role included working with real undercover drug agents. Little did he know, they would prank him, giving him a real scare with a fake drug deal gone wrong. After working with the actor for a week, the agents invited him to sit in on a deal with Colombian suppliers for a large amount of cocaine. Farrell was assured everything would go smoothly because they had established a good relationship with the criminals. The actor eagerly went along as research for Miami Vice, but the meeting went sideways when one of the Colombians revealed a gun and demanded Farrell say he wasn't a cop.
Video of the prank (via YouTube) was included as bonus material with the Miami Vice DVD. In it, Farrell is shown tearing open his shirt to prove he's not wearing a wire as he promises he's not with the police. In reflecting on the fake drug sale, he says, "It was very scary." He also had trouble sleeping that night and called one of the advisors to talk about it. The original plan was to never let him know that he was set up on a fake drug deal, but Farrell was so shaken that he was let in on the joke the next day.
Colin Farrell is known for his rough-and-tumble past. He's publicly addressed his past alcohol and drug use (and days in rehab). It's amusing to think of him falling so readily for a prank, and in turn being shaken by it. Of course, this drug-deal-gone-wrong prank behind the scenes of Miami Vice was way beyond the typical hazing an actor might get during production and Farrell may have legitimately feared for his life in the moment. The cops who were in on it should've been given special Oscars for pulling it off.