As Minnie Driver put it during a Q&A following a special screening of “Good Will Hunting” at the Tribeca Film Festival on Wednesday, the film is “precious.”

“It’s so funny, and it’s so sad, and it’s so full of redemption, and it’s so romantic and full of love. … It’s all genuine, all of those components,” Driver told the audience at the SVA Theatre in Chelsea. “Elliott [Smith]’s music, the way it was edited, Danny Elfman’s score, Gus [Van Sant], every actor in it, every word that was written or improvised, the cinematography — it’s all so beautiful. It’s so amazing for that to come together so gracefully, it’s just rare and precious.”

Director Gus Van Sant, co-star Stellan Skarsgard, psychiatrist Paul Browde and physicist and author Brian Greene joined Driver for the Tribeca Talks: After the Movie event. The group shared some things you may not have known about the award-winning 1997 film, written by its stars, Matt Damon and Ben Affleck.

Here are 7 fun facts we learned about “Good Will Hunting”:

1. Robin Williams and Matt Damon used to joke around in-character in between takes.

During the TFF discussion, Van Sant confirmed that a lot of the lines in the movie were improvised, including the one Sean Maguire (Robin Williams) says after reading Will Hunting’s (Matt Damon) letter at the end of the film: “Son of a bitch. You stole my line.” But the best improvisation happened in between takes, when the crew was setting up shots.

“The one thing that was going on, which is a tragedy I wasn’t rolling the cameras, was — especially in Sean’s office — we would do long takes, and it was on film so we didn’t have modern conveniences, like focus was harder and we had to measure everything. The camera would work its way around the room and the characters were working their way around the room and they would have to freeze while we pulled focus,” Van Sant explained. “So, you’d do the lines to make sure you knew where you were going to be in the room … and Robin [Williams] would do his part as [inaudible] and Matt [Damon] would do his part as Daffy Duck. Then the next time around, Robin would choose a different character, Frankenstein, and Matt would be Nixon.”

“It was really entertaining and a day after that I was like, ‘Isn’t that great, isn’t that fun that you guys are improving that?’ And Matt said, ‘No, it’s exhausting.’ He couldn’t keep up with Robin, Robin’s imagination.”

2. Matt Damon was actually, really asleep during a scene when he was in bed with Minnie Driver.

Because he was producing, writing and starring in “Good Will Hunting,” Damon was, justifiably, beyond exhausted, Driver explained. Before they were ready to shoot a scene between Damon and Driver, the actor fell asleep in the college bedroom set — Skylar’s (Driver) dorm room — during a lunch break.

We had this scene after lunch that took place in the bed, so I think he thought he was just going to get a head start on the whole thing. I remember Jean-Yves [Escoffier], who was the amazing cinematographer, saying, ‘Let him sleep, we’ll just shoot it from above.’ And they just built this structure so you’re above the bed and then Gus was just like, ‘Well just go and get into the bed.’ And, I got in bed and I was like, ‘Babe, you know we got to do the thing,’ and he’s like ‘[mumbles].’ And it was so quiet and it was so sleepy and we did that scene based around him, like, really being asleep. … I loved that everything worked around that. It’s such a beautiful scene, it’s one of my very favorites.

3. Casey Affleck basically created his own character through improvisation.

Some would say Casey Affleck is the comedic relief of “Good Will Hunting,” but his character Morgan O’Mally wasn’t necessarily written as the smart aleck he portrayed onscreen. According to Van Sant, he encouraged improvisation on-set and said Affleck’s moments stood out.

“I like the idea of the actors improvising and when they’re doing it, I don’t stop them,” Van Sant said. “If they are really liking their own improvisation, they’ll encourage themselves and then they’ll continue. I think the ones that were really standing out were like Casey Affleck …”

“He created his part, he really did,” Driver chimed in.

And thank God he did.

4. Matt Damon and Ben Affleck gave the full, original script to Oscar voters so that they could compare notes while watching the final product.

Damon and Affleck ended up winning the Oscar for Best Original Screenplay at the 70th annual Academy Awards for “Good Will Hunting,” and they might’ve used a tactic that put the odds in their favor.

“Matt and Ben did a really cool thing when it was like Academy Award time,” Driver said. “They printed the script so everyone who’s voting could read the script, and they wanted it to be the script that they wrote so that someone could actually watch the film and see where the improv came. There were plenty of scenes that were exactly as written, but plenty of improv in it and I always loved the fact that they wanted you to see that. It was beautifully collaborative and they were so generous in the way that they invited all of us into the story that they created and we made it something else.”

5. Robin Williams would do celebrity impersonations while acting in scenes with Stellan Skarsgard.

Stellan Skarsgard, who plays Gerard Lambeau in the film, admits that he isn’t the best at improvisation, so working alongside Robin Williams was a real treat. Skarsgard said he enjoyed acting with the late comedian because he “fucked up” his performances. (Yes, you read that right.)

“He was constantly improvising and I like that because if you prepare properly, it gets totally trashed by someone else improvising and that’s really good,” Skarsgard explained. “You get a little stiff and too skillful and too elegant if your performance doesn’t get fucked up by someone and he was really good at that.”

Skarsgard went on to detail a specific time when Williams’ impersonations threw him off:

It was the beginning of a rather big scene that ends with him calling me “arrogant prick” or something unfair like that and the first take I came in and it wasn’t him, it was Jack Nicholson there, and he talked like Jack Nicholson, he behaved like Jack Nicholson. I tried to play the scene with him because I’m really bad at improvising, so it became very strange, and then everybody laughed. We had to do it again and I came in and it was James Cagney. I think it was five or six takes with a different person I met in that part every time. And then gradually he’d do something more and more like the character in the film.

Williams won the Academy Award for Best Supporting Actor for his role as Sean Maguire.

6. Will Hunting was originally supposed to be a physics prodigy.

Apparently, Nobel Prize-winning American theoretical physicist Sheldon Glashow, whom Damon met while studying at Harvard University, convinced the actor to make Will Hunting a mathematician rather than a physics genius, due to the fact that it would make more sense for the character.

“It does work better in the sense of, you got this guy, he sees a problem on the board and he goes ahead and solves it. It’s unlikely that someone could look at data by themselves and come up with a theory of the origins of the universe on their own. It just is less believable,” physicist Brian Greene said.

And, believe it or not, the math problems in the movie are not as hard as you’d think. “The first one is actually not a particularly difficult problem,” Greene insisted. “The second one, though, I don’t know what it is. It went by too fast.”

7. Two actors in the movie were actually the brains behind the mathematical operation.

Patrick O’Donnell, who says “bullshit” in a bar scene in “Good Will Hunting,” was actually the man behind the math equations used in the film. He, alongside John Mighton, who plays Gerald Lambeau’s assistant in the movie, created the equations and graphic theorems seen onscreen.

Van Sant met O’Donnell at a restaurant, oddly enough discovering that he was the head of the University of Toronto Mathematic Department. “We needed help with the problems and he hooked us up with John Mighton, who was Tom to [Stellan’s] Gerry,” he said.

As for Skarsgard, he admits he’s not at all like the mathematician he plays.

“[Mighton] actually tried to teach me and make me understand those things, but it was impossible,” Skarsgard joked. “I did the only thing I could: acted.”

Now everyone go home and watch “Good Will Hunting.” Bye.

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