It’s not every day that you hear the origin story of a filmmaker from his mother. But on Saturday, Ellen Liman, mother of director and Chilmark resident Doug Liman, embarrassed her son as only a mother can: with a story of her son’s humble filmmaking beginnings, in the basement of their New York city apartment building.

Ms. Liman offered the story after a screening of Mr. Liman’s new film, The Instigators, at the Grange Hall on Saturday, where she was joined in conversation by her son and Amy Schumer.

“Doug is great at chase scenes, as you saw in this film, of course,” Ms. Liman began. “But his very first one, which I think was maybe 35 years ago, in his very first feature that he did, he cast a cat and a mouse, and he shot them in the in the basement, guerilla style.”

Mr. Liman had hoped to coax a terrified performance out of a lab mouse, so he brought in a cat. But the cat didn’t bother the mouse — instead, the mouse scared the cat, and so an inverted chase ensued.

Amy Schumer joined the Limans onstage for a discussion after the screening. — Noah Glasgow

Mr. Liman shot the whole thing on film stock that he told companies was test stock for another project, he added.

“It was totally illegal, of course,” Ms. Liman said. “He’s always been this indie, guerilla, taking advantage of all kinds of opportunities to fit in things that might not have been there.”

Mr. Liman has come a long way since his early projects, which also included the indie comedy Swingers, which he shot entirely on leftover film stock from the 1996 blockbuster Twister.

But his scrappy attitude continues with his blockbuster work.

In The Instigators, Matt Damon plays a straight-laced Quincy native who joins a misfit crew of thieves for a heist to steal the cash bribes brought in by a corrupt Boston mayor, played by Ron Perlman.

Mr. Damon and a hard-drinking fellow thief, played by Casey Affleck, must navigate Boston’s underworld when the heist goes south. The Instigators was released on Apple TV last weekend.

Twenty years ago, Mr. Liman directed Mr. Damon in The Bourne Identity. When the movie received low scores in test screenings, they reshot nearly a quarter of it in just two weeks, rewriting Mr. Damon’s character in the process. The film went on to become a huge success, anchoring an ongoing franchise.

Mr. Liman said Saturday that he and Mr. Damon took their “working shorthand” from Bourne Identity to The Instigators, which Mr. Damon produced alongside his longtime collaborator and childhood friend Ben Affleck.

In The Instigators, Mr. Damon and Casey Affleck break into Boston City Hall; blow up a Quincy home; and drive a fire truck through Boston’s downtown.

“Very simply, if you’re shooting in Boston with Matt Damon and Ben Affleck... they pick up the phone and call the mayor, they call the governor, and they’re so beloved in Boston” that all the pieces just fall into place, Mr. Liman said.

The constant stream of Boston locations, accompanied by a stream of jokes about the Boston bred, makes for a perfect New England–themed summer ride.

Mr. Liman divides his time between New York and Martha’s Vineyard, when he’s not shooting a film in Boston, Los Angeles or elsewhere.

At the end of the evening’s discussion, Ms. Schumer asked how, of all places, Mr. Liman had wound up on the Vineyard. Staying for the summer in his parents rental on the north shore years ago, Mr. Liman said, he had paid a visit to the Chilmark flea market.

“I bought a KitchenAid mixer for $5 and I was like, one day I’m gonna have a house here, and I’m gonna put this mixer in that house,” Mr. Liman said, his thrift find on display. The mixer had no bowl or attachments but, like other things, they would all fall into place in time.

“That’s still the mixer in my kitchen here.”