Actors Michael J. Fox (Marty McFly), Lea Thompson (Lorraine Baines-McFly), Christopher Lloyd (Dr. Emmett "Doc" Brown) and Thomas F. Wilson (Biff Tannen) appeared together at Fan Expo Boston. It was the first time the four had gathered together since a 30th anniversary reunion in 2015, Deadline noted.
The actors shared images of the reunion on Instagram, including Thompson, who wrote: "Four old friends get back from the future."
"Back in 2018, even Biff made it," Fox wrote on Instagram.
"Wow," wrote Wilson. "This just happened."
"This was special," wrote Lloyd.
The actors appeared for photos, autographs and a panel discussion. Tickets to meet the stars, take pictures and obtain autographs sold for as much as $999.
Thompson noted that a large number of fans wore puffy McFly vests, despite the summer heat.
"I'm impressed with all these people in these vests," she said, according to MassLive. "It's 100 degrees and everyone's wearing these vests."
Fox added he actually hated the now-instantly recognizable getup.
"It looked great but it was terrible to wear," he said.
Naturally, the question of a possible (and pretty unlikely) fourth film came up.
"Basically, I think America is saying, 'Come on, they've wrecked every other franchise with bad sequels, why not this one?'" Wilson cracked, per MovieWeb. "C'mon, we would watch it until it sucks."
While a new sequel or reboot would no doubt be a box office monster, there are two pretty big obstacles: filmmaker Robert Zemeckis and writer/producer Bob Gale, who hold the rights to the series and are both adamantly against it.
"Oh, God no," Zemeckis told the Telegraph in 2015 when asked about rebooting the franchise. "That can't happen until both Bob and I are dead. And then I'm sure they'll do it unless there's a way our estates can stop it."