Trivia: When Charlie and Frank fly from Boston to New York there is an airport scene before they depart, but the airport in this scene is Newark Liberty Airport in New Jersey, which is already by New York and very far from Boston.
Trivia: When Charlie is talking to Colonel Slade, the Colonel mentions how he calls the whiskey "John" Daniels because he has known him for a long time. In fact, Jack Daniel's real name is not John, it is Jasper Newton Daniel.
Answer: He's not mentally ill. He was an arrogant, high-ranking military officer who blinded himself in a stupid accident which ended his career. He is now bitter, lonely, and sad. His outbursts are fueled by his anger, regret and the total loss of his former life and independence. He has become so emotionally despondent that he wants to end his life. I have to add, this is Al Pacino, and his acting tends to be over the top in most of his post "Godfather I and II" movies.
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