Peter Sellers having recently come up in the comments, I am reminded of this, the second best scene in the best Pink Panther movie, A Shot in the Dark.
The best scene, of course, is the confession scene, especially when Sellers looks with complete bafflement at the audience as the case solves itself. A Shot in the Dark is interesting in that it was not originally written to be a n Inspector Clouseau movie; it was supposed to be a movie adaptation of a stageplay, Harry Kurnitz's English adaptation, also called A Shot in the Dark, of Marcel Achard's adultery-themed comic mystery play, L'Idiote. It was then rewritten (massively) at the last minute to make Inspector Clouseau the detective, due to the kind of chain of events that dominates Hollywood movie-making -- they wanted Sellers for the story, who was reluctant to do it, but who had enjoyed doing The Pink Panther, which he had just finished; he asked if Blake Edwards, the director for The Pink Panther, could direct this one; Blake Edwards's condition for directing was that it be a Pink Panther sequel; the producers, who had been losing money in delays and false starts , agreed, despite the fact that The Pink Panther hadn't been released yet, and nobody could have guessed how popular it would be. I think this greatly contributes to the film's success; it is, for instance, the reason that Clouseau's obtuseness is not mere incompetence (which gets very tiring, as can be seen in some of the later Pink Panther films) but partly due to the fact that he is obviously and foolishly head over heels in love with the obvious suspect, since this is in the original, although played by a much more straightlaced character than Clouseau. A number of other things were done last minute with the film, including the introduction of the famous exaggerated French accent with the meurths in the closet, the beump on the head, and the exploding beum, and another one of the great scenes, the watch synchronization scene, which was done completely impromptu. Sellers thought the movie was a disaster and tried to convince the production company not to release it (Sellers seems to have had this kind of reaction more than once) and reviewers thought it confusing and shallow, but audiences loved it and it has become widely regarded as one of the great comic films, in part because it is the last very popular film where we see almost all the major forms of Hollywood humor -- silent-film-like sight gags and slapstick, classic comedy, situation incongruity, farce, screwball, sophomoric humor -- all holding together in a form that makes at least some kind of loose sense.