Mrs Doubtfire director has 972 boxes full of never-before-seen footage because Robin Williams improvised so much

Mrs Doubtfire's director has revealed he has nearly 1,000 boxes of unseen film of Robin Williams.

The iconic comedy-drama starring the legendary Williams first came out in the US on 24 November 1993.

To mark the movie's upcoming 30th anniversary, Mrs Doubtfire director Chris Columbus has reflected on what it was like working with Williams.

Columbus revealed Williams set the precedent early on in filming he would be improvising a lot.

The director tells Business Insider: "He went to me, 'Hey boss, the way I like to work, if you’re up for it, is I’ll give you three or four scripted takes, and then let’s play.'

"By saying that, what he meant was he wanted to improvise. And that’s exactly how we shot every scene.

"We would have exactly what was scripted, and then Robin would go off and it was something to behold."

20th Century Fox

Columbus notes he pitied the 'poor script supervisor' who had to 'handwrite' everything Williams said - the actor changing it 'every take'.

"So Robin would go to a place where he couldn’t remember much of what he said. We would go to the script supervisor and ask her and sometimes she didn’t even get it all," Columbus continues. "Often, he would literally give us a completely different take than what we did doing the written takes."

And Williams improvised so much on 'several occasions' all the camera's film would run out, Columbus having to 'shoot the entire movie with four cameras to keep up with him'.

He adds: "None of us knew what he was going to say when he got going and so I wanted a camera on the other actors to get their reactions."

"For Pierce Brosnan and Sally Field, it was quite difficult for them not to break character."

In the end, they shot 'almost two million feet of film' on the movie.

And the director doesn't 'think' the studio watched all of it, which means there's footage of Williams that may never have been seen before.

Getty Images/ Jay Paul

Columbus has since been left with 'roughly 972 boxes of footage' from the movie as a result of Williams' non-stop improvisation.

The boxes include footage used in the movie, but also 'outtakes and behind-the-scenes footage' and is stored 'in a warehouse somewhere'.

And the director has plans for the film reels, hoping to hire an editor to go through all the footage and potentially make a documentary about the making of Mrs Doubtfire.

Columbus resolves: "We want to show Robin’s process. There is something special and magical about how he went about his work and I think it would be fun to delve into it.

"I mean, there’s two million feet of film in that warehouse so there could be something we can do with all of that."

So, any editors out there want to lend a hand?