Robin Williams’ unpredictable and inexhaustible improvisation on hit comedy Mrs Doubtfire meant that film-makers shot “two million feet” of film during its production, according to its director Chris Columbus.

Columbus was speaking to Business Insider to mark the 30th anniversary of the film’s original release in 1993, and said more than 900 boxes of footage are in storage and could be used in a documentary about Williams’s process. “Footage we used in the movie, outtakes, behind-the-scenes footage; it’s in a warehouse somewhere and we would like to hire an editor to go in and look at all of that … There is something special and magical about how he went about his work and I think it would be fun to delve into it.”

A comedy about a divorced man who disguises himself as an elderly nanny to reconnect with his children, Mrs Doubtfire was directed by Columbus and starred Sally Field and Pierce Brosnan alongside Williams. It was adapted from Anne Fine’s novel Madame Doubtfire, and became the second highest box office hit in 1993.

In the interview, Columbus recalled how the production logistics were built around Williams’s particular capabilities. “Early on in the process, 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.

“It got to the point that I had to shoot the entire movie with four cameras to keep up with him. None of us knew what he was going to say when he got going so I wanted a camera on the other actors to get their reactions.”

Columbus also revealed he had discussed the possibility of a Mrs Doubtfire sequel with Williams shortly before the actor’s death in 2014, saying that while Williams appeared amenable, he was less than positive about the extensive makeup and prosthetics required. “We had a script that was written and it was the last time I saw Robin. I went to his house and we sat down and talked about it and the script was really strong. Robin’s only comment was: ‘Boss, do I have to be in the suit as much this time?’ It was physically demanding. For Robin, I think it was like running a marathon every day he was in the Doubtfire costume.

“I think he was hoping in the rewrite we would cut back on the Doubtfire character. But then Robin passed away so there will never be a sequel.”