8. Annie Hall - The Cocaine Sneeze
In Annie Hall, neurotic Jewish comedian Alvy Singer (Woody Allen) is at a party when his friend passes him a small tin filled with cocaine. As Alvy takes the tin in his hands he has a violent sneeze - sending white powder everywhere. The surrounding actors’ uncontrollable laughter was spontaneous and genuine and Allen decided to leave it in the final cut of the film after it tested well with audiences.
So one of the most famous sneezes in cinema history was never actually intended to be part of the final film - it actually occurred during a scene rehearsal.
7. The Shining - Here's Johnny!
Wendy Torrance (Shelley Duval) and her son Danny (Danny Lloyd) hide from the deranged novelist Jack Torrance (Jack Nicholson) in a hotel bathroom. As Jack begins chopping through the door with a fire axe and sticks his face into the splintered opening, he utters a phrase previously made popular by Ed McMahon on The Tonight Show starring Johnny Carson - "Here's Johnny!"
The line was not part of Kubrick's original screenplay for The Shining and was improvised by Nicholson.
6. Blade Runner - Like Tears in Rain
As ex-Blade Runner Rick Deckard (Harrison Ford) attempts to "retire" the replicant known as Roy Batty (Rutger Hauer), he finds himself in a precarious position. The battle worn replicant shows mercy on Deckard rescuing him from the edge of the building - only to "die" shortly after giving a moving monologue.
As he reminisces about his past he says, "All those moments will be lost in time...," but then Hauer adds the unscripted and philosophical phrase "...like tears in rain."
5. Midnight Cowboy - I'm Walkin' Here!
As Midnight Cowboy's want-to-be gigolo Joe Buck (Jon Voight) and crippled scam artist Ratso (Dustin Hoffman) cross a street in New York City, a REAL NYC taxi cab driver who ignored all the "Street Closed for Filming" signs drives through the scene.
Obviously this wasn't scripted and Hoffman's response and actions were all improvised, in character, as a result.
4. A Clockwork Orange - Singin' in the Rain
A Clockwork Orange's Alex (Malcolm McDowell) breaks into a happy song as he and his "droogs" perform a bit of "ultra-violence" and rape. Reportedly Kubrick filmed this scene several times and wasn't happy with it each time - until he told McDowell to just "do anything he wanted".
McDowell decided to belt out "Singing in the Rain" and Kubrick was so pleased with how much better the scene became that he acquired the rights to use the song immediately.
3. Taxi Driver - You Talkin' to Me?
When Taxi Driver screenwriter Paul Schrader wrote this scene it simply said "Travis talks to himself in the mirror" - there was no specific dialog given. Everything that insomnia-plagued taxi driver Travis Bickle (Robert De Niro) says during his faux-conversation was improvised by De Niro on the spot.
To this day, whenever someone walks by a mirror they can't help but utter his now famous line "You talking to me?"
2. The Silence of the Lambs - Hannibal's Hiss
The famous "hssssss" sound made by Dr. Hannibal Lecter (Anthony Hopkins) during his story about eating a liver with "fava beans and a nice Chianti" to FBI agent Clarice Starling (Jodie Foster) wasn't in the original script for The Silence of the Lambs.
Apparently, it was something Hopkins did during rehearsals to creep out Foster - and Demme decided leaving it in was the best way to creep out his audience too.
1. Full Metal Jacket - Gunnery Sgt. Hartman
Originally, R. Lee Ermey wasn't even cast in the role as Gunnery Sergeant Hartman in Full Metal Jacket but after Ermey submitted a tape of himself spewing insults at group of Royal Marines for 15 minutes straight, Kubrick cast him immediately
Ermey wrote 150 pages of insults and Kubrick estimated that 50% of the character’s dialog was improvised by the former drill instructor.