Directors and writers spend months, sometimes even years perfecting a movie scripts.

So you might be surprised to know that some of the most iconic moments from the world’s most popular films were in fact improvised.

Here are a whole bunch of scenes that weren’t scripted, yet still made the final cut. You’ll never watch these movies in the same way again.

Raiders Of The Lost Ark

In the script for the Raiders Of The Lost Ark,  it simply said “big sword fight”. However Harrison Ford was sick and wanted the scene to be over with. After the character dressed in black makes a big entrance, Ford shoots him – this was kept and was actually used in the movie.

The Godfather

All Godfather impressions are not complete without mimicking the stroking of a cat. However the moggy wasn’t planned at all. Brando actually found the kitten wandering around the movie set that morning and decided to pick him up. The rest is history.

The Dark Knight

When it’s announced that Commissioner Gordon has a promotion, the Joker begins to creepily clap. This was a spur of the moment ad lib from Heath Ledger and was not planned.

Pretty Woman

When Richard Gere’s character offers Julia Roberts a necklace and then snaps the box shut, this was just a practical joke. But Julia’s laugh was so real, the producers decided to leave it in the movie.

Caddyshack

One of the more memorable parts of this movie sees Bill Murray’s character mumble a story about an unknown golfer winning The Masters. This was something that Murray made up on the spot.

Dumb And Dumber

None of the fight in the awkward car scene was scripted. The actors simply went with their instincts. You can see the genuine wonder on the actors faces when Jim Carey’s character asks “Want to hear the most annoying sound in the world?”.

Aliens

The often quoted “game over” from Aliens, said by Private Hudson was never actually in the script, yet is one of the more memorable lines.

Tootsie

Bill Murray played Jeff Slater in Tootsie and during the party scene Murray was required to talk non-stop – however their was no script. Murray actually made it all up.

Jaws

“You’re going to need a bigger boat” is the biggest line from Jaws but it was actually a spontaneous remark from Roy Scheider’s Chief Brody.

The Shinning

“Here’s Johnny” is a line that will go down in as cinematic history, not only due to being so iconic but also because Jack Nicholson made it up completely – it was never in the script.

Terminator 2

When the T800 old model terminator nearly gets destroyed, Arnie ad-libbed the line “I need a vacation”. The timing was perfect but completely unplanned, the actor just got the idea from a script note on the appearance of the robot.

Shaun Of The Dead

Shaun, played by Simon Pegg, is left laughing in the pub scene alongside Nick Frost’s Ed, as Ed tells a bunch of funny stories to cheer him up. In this scene Pegg’s laughter was real and Frost was making the stories up on the spot, Pegg hadn’t heard them before.

Good Morning Vietnam

In the Robin Williams classic, none of the broadcasts were scripted. Williams made each one up as they filmed making the classic what it is today.

50/50

In the movie Joseph Gordon-Levitt takes a razor to his head and removes all of his hair. The look of shock and horror on Seth Rogen’s face is completely real as this was never in the script.

Tarzan The Ape Man

It turns out the famous cry that Tarzan is now known for was in fact ad lib from the actor who first played him, Johnny Weissmuller. Weissmuller was actually a yodeller in personal life and came up with the call when the script asked him to perform a call that would bring all of Tarzan’s jungle friends together.

Zoolander

David Duchovny patiently explains to Derek Zoolander, played by Ben Stiller, why there will be male models. Stiller then says: “Why male models?”. This was actually a mistake and Stiller had forgotten that he had already asked the question – but it suited the character perfectly so they kept it in.

Blade Runner

When Roy Batty, played by Rutger Hauer is dying on the roof he says: “All these moments will be lost like tears in the rain. Time to die,”. There was actually several pages of dialogue for this scene but Hauer didn’t think it added up so he made his own lines instead.

Star Wars: The Empire Strikes Back

When Princess Leia, played by Carrie Fisher tells Han Solo, Harrison Ford, that she loves him, he simply replies: “I know”. However he was supposed to say “I love you, too”. At first George Lucas was not impressed with the ad-lib but eventually the rest of the cast convinced him to keep it.

The Godfather

This is arguably one of the most famous lines from The Godfather, but when Richard Castellano said: “Leave the gun. Take the cannoli” he actually added the second bit himself.

The Jazz Singer

“Wait a minute. Wait a minute. You ain’t heard nothin’ yet” is the famous line from Al Jolson (Jakie Rabinowitz) in The Jazz Singer.  This was definitely unscripted as the whole movie was supposed to be silent.