According to the remaining cast members, Mr. T and George Peppard did not get along. Peppard was a "proper movie actor," but Mr. T became the real star of the show. Things got even worse when Peppard learned Mr. T was being paid more than he was.
Despite his insanity and quirky personality, Murdock has an almost genius-level aptitude. He has a vast knowledge of many subjects and keeps up on current events. He's also fluent in Chinese (Mandarin), German, Japanese, Spanish, Vietnamese and basic Russian. He can communicate in Morse Code and has a photographic memory. In fact, dialogue in season 1 suggests that he may not even be as "mentally unstable" as some characters may think he is.
In the opening credits, Dirk Benedict reacts to a passing metallic "Cylon warrior." Cylons were the nemesis in Benedict's earlier series, "Battlestar Galactica (1978)", in which he played Lieutenant Starbuck.
NBC executives originally wanted the character of Murdock to be removed from the show because they felt that he was too over-the-top. However, test audiences loved Murdock and gave him the highest ratings. The executives had to relent.
Three cast members have prior U.S. military experience: George Peppard served in the Marines, Eddie Velez served in the Air Force, and Mr. T was an MP in the Army.