The show is famous for the unusually high turnover rate among the regular cast, partially due to contractual disagreements between the cast and the producers. Almost all of the show's major characters were killed or otherwise removed within a season or two of being introduced. In fact, the only character to appear as a regular during all five seasons was FBI Agent Ronald Sandoval (Von Flores), the show's main antagonist.
Peter Outerbridge and David Hewlett were considered for the role of William Boone.