Robin Williams ran wild with improv while making Mrs. Doubtfire.

Mrs Doubtfire (On Set)

Chris Columbus and Robin Williams on “Mrs. Doubtfire” set. PHOTO: MOVIESTORE/SHUTTERSTOCK

In honor of the 1993 film’s 30th anniversary, director Chris Columbus recalled making the comedy classic, which also starred Sally Field, Pierce Brosnan, Harvey Fierstein and Mara Wilson.

Columbus, 65, told Business Insider that Williams improvised so much on set that they ended up using “almost 2 million feet of film.”

“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,’ ” the director remembered. “By saying that, what he meant was he wanted to improvise. … We would have exactly what was scripted, and then Robin would go off and it was something to behold.”

The director said it was “quite difficult” for costars Brosnan and Field “not to break character” as Williams went off-script with new gags while filming.

“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 and so I wanted a camera on the other actors to get their reactions,” said Columbus.

Robin Williams Mrs Doubtfire - 1993

Robin Williams in “Mrs. Doubtfire” (1993).20TH CENTURY FOX/BLUE WOLF/KOBAL/SHUTTERSTOCK

Asked if there are plans to ever show the excess footage they captured while making Mrs. Doubtfire, Columbus said he wants to utilizes the material for a documentary.

“We are talking about it and trying to get it done,” he said. “There are roughly 972 boxes of footage from Doubtfire — footage we used in the movie, outtakes, behind-the-scenes footage — in a warehouse somewhere and we would like to hire an editor to go in and look at all of that footage.”

“We want to show Robin’s process,” said Columbus of the Oscar-winning actor/comedian, who died in 2014 at age 63. “There is something special and magical about how he went about his work and I think it would be fun to delve into it.

He joked, “I mean, there’s 2 million feet of film in that warehouse so there could be something we can do with all of that.”

Brosnan told GQ last year about one of the film’s memorable moments that Williams improvised: the “run-by fruiting,” in which his character Stuart Dunmeyer got hit in the back of the head with a lime thrown by Mrs. Doubtfire.

“It wasn’t in the script,” Brosnan said of the line. “I get the beers, I’m walking back and thinking, ‘This is going to take forever to hit me on the head.’ The first one missed. And the second one — is history.”