1. Robin Williams' last line in the film was ad-libbed.
2. And the whole "farting wife" scene was unscripted.
That Matt Damon laugh is as genuine as it comes. In the original script, Sean tells Will a story about how his wife used to turn an alarm clock off in her sleep.
3. The role of Skylar was based on Matt Damon's ex-girlfriend Skylar Satenstein, whom he met at Harvard.
4. Matt Damon and Minnie Driver dated during production, but their romance eventually came to a very rocky end.
5. The character of Sean is based on a combination of Matt Damon's mom and Ben Affleck's dad.
6. Minnie Driver almost didn't get the part of Skylar.
7. Chuckie takes Will's place at a meeting with a company called Holden & McNeil. Holden McNeil was the name of Ben Affleck's character in Chasing Amy.
8. The picture of the boat in Sean's office was actually painted by director Gus Van Sant.
9. The script for Good Will Hunting started as a class assignment.
10. Matt Damon and Ben Affleck used to slip Sean and Will sex scenes into the script.
11. Damon really liked his '90s frosted tips (at the time).
12. Casey Affleck ad-libbed a bunch of his lines.
13. Damon and Affleck cried the first day of filming.
It was during a scene with Stellan Skarsgard and Robin Williams.
Damon said, "When Gus called action and we watched these guys — I mean accomplished actors — do our scene verbatim, we had waited so long for this to happen. I remember just sitting next to Ben and I had tears rolling down my cheeks because I was just so happy and relieved that it was really happening.