One of the best on-location street scenes in movie history was actually an accident (although there are some naysayers who say the shot was scripted). When "Ratso" Rizzo (Dustin Hoffman) yells, "I'm walking here!" to a New York City taxi driver in Midnight Cowboy (1969), the cabbie was a real-life cabbie. To save money, Director John Schlesinger did not file a permit with the city to use the Midtown Manhattan street for his film. The scene is a "stolen shot," which in film rhetoric means the director did not get official permission to shoot on a city street. The pedestrians are real New Yorkers, not extras. Their surprise is not canned. The cameramen were poised in a van a block away, shooting the scene. The cab driver is an actual pissed off cab driver. No extras on set.
Hoffman is brilliant in this scene. He does not break character. He keeps Ratso's limp intact (evidently Hoffman kept pebbles in his shoe to keep his limp consistent for every shot). His cigarette falls to the ground; he doesn't bother to pick it up. When his buddy (John Voight) looks stunned, Hoffman pulls him along by the arm. Hoffman's adlib is perfect; after a near brush with a yellow cab, he keeps it hot, muttering in character, "Actually, that ain't a bad way to pick up insurance, you know"; you can tell Voight is a little surprised by the interruption, but even still, he stays in character.