Dudley Moore was said to have based his performance partly on Peter Cook, whose excessive drinking had soured his and Moore's comedic partnership in the '70s.
There's a framed photo of Harry S. Truman on Arthur's father's desk. The other photo, to the left of Harry S. Truman, is that of Winston Churchill, and it appears to be autographed.
Bud Cort was originally suggested for the role of Arthur.
John Gielgud turned down the role of Hobson several times, finally accepting it only because the salary he was offered was too good to pass up.
At one point during the production, Liza Minnelli is supposed to board a bus in front of Bergdorf's on Fifth Avenue. When a real bus came along, she boarded it thinking it was the "movie bus". Not until she was halfway down the block did she realize her blunder when she looked back and saw the whole crew cracking up.
The scene where Arthur drives his "racing car" around a track was shot at the now defunct Danbury Fair Racearena in Connecticut. The type of car that Arthur drove was never raced there, it was primarily for Modified stock cars and was one of America's great short tracks. Sadly, despite its great success, the land became too valuable and it gave way to a shopping mall. The Danbury Fair Racearena closed on October 12, 1981, shortly after the movie was filmed.
According to his widow, John Belushi was offered the role of Arthur, but ultimately turned it down, fearing typecasting.
Kay Lenz wanted badly the female lead role, because her previous attempts to be a movie star failed.
Tuesday Weld was originally offered the role of Linda Marolla but turned it down.