Robin Williams takes centre stage in rare rehearsal footage that’s been released by Jack director Francis Ford Coppola after 30 years.

This week marks three decades since the release of the Godfather filmmaker’s family comedy Jack, in which Williams played a young boy who ages four times faster than normal due to a unique medical condition.

To mark the anniversary of the film’s premiere, Coppola shared a behind-the-scenes clip in which Williams can be seen joking about his child co-star, Adam Zolotin.

“I loved making Jack and thought it was imaginative and unusual, despite the fact that the theme had been dealt with perfectly in Big by Penny Marshall,” Coppola wrote on Instagram. “And the ending of Jack is very touching.”

He continued: “In this rehearsal clip with Adam Zolotin, the two adlib their way playfully through song, with the young Louis coercing his nervous friend to pretend to be the principal so that he won't get in trouble with his mother.”

Jack, which also stars Diane Lane, Jennifer Lopez, Brian Kerwin and Fran Drescher, received negative reviews at the time of release, but critics praised Williams. That decade, Williams also starred in films such as Toys (1992), Mrs Doubtfire (1993), The Birdcage (1996), Flubber (1997) and Patch Adams (1998).

He also voiced the Genie in Disney's Aladdin in 1992 and won an Oscar for his role in Good Will Hunting (1997).

One of Williams’s best-loved films was Jumanji, which was released the year before Jack, in 1995.

During his time on Jumanji, Williams stepped in to defend child star Bradley Pierce from over-demanding producers.

Alongside Kirsten Dunst, Pierce played one of the kids in the hit family film; in 2020, he recalled shooting a sequence in which the titular game leads to a fierce monsoon.

The actor, who was 13 at the time, was having trouble breathing in the scene due to the water and his extensive makeup. In the film, his character is transformed into a monkey.

“I couldn’t breathe through my nose,” he told CBCListen, adding that the shoot, which lasted for eight days, “was really draining for everybody” and left him “tired”.

Despite this, Pierce recalled that producers attempted to get the child stars to work overtime, which is not legally permitted.

“Children can only be on set for a number of hours,” Pierce said. “The producers had approached our parents and said, ‘Is there any way we can do a bit of overtime to get it done?’

“That’s not uncommon at all in the industry because it literally saves $100,000 (£73,000) plus to do that extra half hour rather than a whole day.”

Williams, however, “caught wind of these conversations” and “pulled the director [Joe Johnston] and producers aside” to tell them that wouldn’t be happening.

“He said, ‘No, we are not doing any extra time. You’re going to let everybody out now and we’re going to come back next week,’” recalled Pierce.

He added: “For all the dollars that would have cost, nobody would have stood up the way he did. In addition to being warm, generous and kind, he was also very protective.” * *

Williams died by suicide in 2014, aged 63; an autopsy found that the actor had been suffering from Lewy body dementia for the last years of his life.