By Hillary Busis
October 16, 2013 at 02:36 PM EDT

“I have a feeling that Mystic Pizza may someday become known for the movie stars it showcased back before they became stars,” Roger Ebert wrote upon the film’s release in 1988. He wasn’t kidding: Though this smart coming-of-age comedy has plenty of merits, it’s best known today for introducing the world to a feisty Georgia native with a megawatt smile named Julia Roberts.

“Miss Roberts here — you just knew when she met Julia she was gonna be a huge star,” the Oscar winner’s Pizza costar Vincent D’Onofrio told EW’s Jess Cagle when the movie’s cast reunited for the magazine’s annual Reunions Issue. (Roberts’ response? A skeptical look and a gentle “Shut up!”) “There was no doubt in our minds, any of us,” he continued. “She was like a bomb waiting to go off. A big bomb!”

Of course, no one in the cast could have guessed that one of the film’s bit players would wind up winning an Oscar of his own someday. At one point in Pizza, Roberts’ character is invited to dinner at the home of her rich boyfriend (Adam Storke). Another guest at the table? The boyfriend’s little brother, played by none other than Matt Damon in his very first big screen appearance.

“He actually looked like Jason Bourne,” Storke joked during the reunion.

Which of Mystic Pizza‘s actors was the most intense on set? Who was the happiest? And what does Roberts choose as her most memorable scene? You’ll find all the answers in this reunion video, which aired Wednesday on Good Morning America — well, except the truth of what was really in Leona’s special sauce.