Templeton "Faceman" Peck was originally played by Tim Dunigan, but he was fired after the pilot and replaced by Dirk Benedict because the producer decided that he was too young for the part.
Season 1 clearly sets up that John "Hannibal" Smith is a jobbing actor, that happens to work at Universal. This also explains his access to make-up, costumes, props, set dressings, etc over the entire series run.
Throughout the entire run of the series, only once did any member of the team call Hannibal by his real name - John. It was done by Face in this episode. Although in the fifth and final season, new team member Frankie Santana did have the audacity to refer to Hannibal as 'Johnny'.
SERIES TRADEMARK: This is the only episode in which Hannibal's Chinese alter-ego Mr. Lee appears on-screen. He is often referred to by the team's clients in later episodes.
Tim Dunigan was replaced by Dirk Benedict because producers felt he looked too young to be believable as a Vietnam War veteran, but it is also rumored that he was too tall next to his fellow A-Team cast members.