Casboult was recruited by the Carlton Football Club with its third round selection in the 2010 AFL Rookie Draft (at selection 44 overall). His first month at the club was eventful. Before the 2009 Christmas break, Casboult attended the team's controversial booze cruise (the fallout from which included the suspensions of Andrew Walker, Eddie Betts and Ryan Houlihan, plus a "please explain" to the club from the AFL); it was widely reported in the media that, in an initiation game, Casboult was handcuffed to an unnamed senior player and forced to match him drink-for-drink until barely conscious. A few days later, on 24 December, Casboult was fortunate to walk away uninjured from in a head-on car accident: his car was struck by the car of Samir Azemi, which had jumped the median strip on the Princes Highway in Dandenong. Azemi was killed in the accident.