…Except when it doesn’t. What happens when you don’t have a finished script but production must commence? Or when actors keep changing an existing script on the fly? Often times, that’s when improvisation plays a big role—which can be risky, but can also result in a film’s best moments. Here are several amazing movies that either started without scripts or relied on improvisation for a good chunk.

12. Before Sunrise (1995)

Technically, Before Sunrise wasn’t improvised despite rumors of it, which arose from its true-to-life realism. But Before Sunrise didn’t have a solid script from start to finish, either. In fact, director Richard Linklater worked closely with writers and actors to continually rework the scenes as they went through filming. As the first film in the Before trilogy, Before Sunrise was shot in chronological order on a tiny budget, often relying on Vienna’s public transportation system to keep its wandering traveler themes. Linklater even stayed up until 3AM rewriting the finale the day before shooting, alongside stars Ethan Hawke and Julie Delpy.

11. The 40-Year-Old Virgin (2005)

Like many comedies, a large portion of The 40-Year-Old Virgin was improvised. Actress Catherine Keener stated that the director, Judd Apatow, never really told the cameraman to cut, which allowed many scenes to unfold and evolve naturally. One particularly memorable part is when Steve Carell—who plays the titular 40-year-old virgin—has his chest waxed. His reactions to the pain weren’t scripted, and the laughter of his co-stars Seth Rogan and Paul Rudd is genuine. Comedy gold!

10. This Is Spinal Tap (1984)

Rob Reiner’s cult mockumentary (stylized as This Is Spinal Tap: A Rockumentary by Martin Di Bergi) received acclaim for its humor and smart direction. It basically gave birth to the mockumentary subgenre. Around 50 hours of improvised footage were recorded by the end of production, which was then relentlessly whittled down to less than an hour of screen time. Rob Reiner, alongside starring actors Christopher Guest, Michael McKean, and Harry Shearer, even went to the Writers’ Guild to ask that the performers be credited for their script contributions!

9. Iron Man (2008)

In a world full of superheroes and multiverses, you’d never guess Iron Man was made on a whim. Today’s big-budget Marvel blockbusters take tons of meticulous planning and choreography, but Iron Man didn’t even have a full script to begin with. Robert Downey Jr. was having a tough time in the media. About 30 writers passed on penning the script. The studio wasn’t entirely sold on the idea of a superhero film that could be successful. So, director Jon Favreau pretty much went in blind. Downey Jr.’s co-star Jeff Bridges confessed to arriving on set without a clue of what to do, and he was surprised to see the film end up as a box office success that launched the entire Marvel MCU.

8. Borat (2006)

Borat (or: Borat! Cultural Learnings of America for Make Benefit Glorious Nation of Kazakhstan) is the second mockumentary on this list, and it’s another iconic film built on improvised comedy and real-life gags. While the sequel had a solid script, this first entry in Sacha Baron Cohen’s comedies was born from unscripted interactions with the public. Under Larry Charles’ direction, Cohen poses as a Kazakh television journalist traveling through the US. The black-comedy stirred up a lot of shocked, appalled, and hilarious reactions—and all of them were real!

7. My Son (2021)

Christian Carion’s recent mystery thriller did technically have a script, but not all of the actors got to see it. The crew and most of the cast—including Claire Foy—were given a copy of the screenplay and months to rehearse. The main star, however, was given nothing. James McAvoy admitted in an interview on The Graham Norton Show that all of his dialogue was made up on the spot as he improvised against his co-stars’ scripted reactions. With nothing but a loose outline to his name, McAvoy did an exceedingly good job, even if some scenes didn’t go as planned.

6. Blue Valentine (2010)

Derek Cianfrance’s romantic drama Blue Valentine bites with realism, and he really tapped into its grainy and authentic feel by filming its scenes with a hand-held camera. Ryan Gosling and Michelle Williams star as the young and old version of a couple whose marriage falls apart. In preparation, the two actors rented a home together and bought groceries on the same minimal budget as their characters. Why did they do this? To really know their roles and leave much of the dialogue to improvisation. Cianfrane even confessed that he got annoyed when the actors followed the script without adding anything new. Fun fact: the Blue Valentine scene in which the two wander New York together is completely unscripted.

5. Jaws (1975)

Jaws was essentially the first summer blockbuster ever made. The endlessly quotable classic, based on the 1974 novel by Peter Benchley, was the second in Steven Spielberg’s soon-to-be lengthy filmography. The young director wanted a natural feel to the thriller flick, so he often let the actors make up their own lines. In fact, they didn’t even have a finished script before they launched out to sea and began filming! Co-stars Richard Dreyfuss and Robert Shaw practically hated each other on set, which translated well onto screen as rivals Hooper and Quint.

4. The Blair Witch Project (1999)

This one’s probably not much of a shock, given the found-footage style of filming. Daniel Myrick and Eduardo Sánchez’s iconic supernatural horror became an instant cult classic thanks to its gonzo filmmaking techniques that achieved its “recovered footage” atmosphere. Myrick and Sánchez came up with the idea of the “Blair Witch” myth back in 1993, and five years later produced a micro 35-page script. Actors Heather Donahue, Michael Williams, and Joshua Leonard were left to improvise a majority of the dialogue—and with their success, The Blair Witch Project spawned a whole genre of found-footage horrors.

3. Lawrence of Arabia (1962)

The success and scope of Lawrence of Arabia may trick you into thinking that everything was meticulously planned, when really nothing could be further from the truth. Okay, that’s not quite true—a lot of the production was indeed thought out quite well. However, it’s definitely true that director David Lean began filming Lawrence of Arabia without a finished script at hand. That might be a reasonable approach for a small-budget indie flick. But a four-hour historical epic as ambitious as this one? Now that’s risky. Funny enough, once a finalized script was scrabbled together, co-stars Peter O’Toole and Jack Hawkins still ended up improvising their scenes together, much to Lean’s frustration!

2. Casablanca (1942)

Though now considered one of the greatest films of all time, Warner Bros. assumed Casablanca would just be another run-of-the-mill war film, so they didn’t waste too much energy on pre-production. In fact, there’s still no completed script for Casablanca in existence. That famous line (“Here’s looking at you, kid”) was made up by Humphrey Bogart on the spot. After it was chaotically compiled into a loose screenplay and then filmed, Michael Curtiz’ drama was rushed to release for publicity purposes (“Operation Torch” had just broken out in North Africa) and was never expected to be considered one of the greats.

1. Apocalypse Now (1979)

Apocalypse Now had a famously hellish production, involving all manner of issues from drunk actors, to heart attacks on set, to bad weather destroying sets entirely. Due to its multitude of problems, much of the movie had to be reworked in real-time. Francis Ford Coppola filmed for hours at a time to allow Marlon Brando to ramble (as he was unable to remember his lines). The famous opening scene of Martin Sheen drunk in the hotel room didn’t follow a strict script, either. The actor really was drunk, and he really did cut his hand punching that mirror. Yikes!

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