As part of the latest episode of his new YouTube series, Reunited Apart, Gad was joined by Christopher Lloyd, Michael J. Fox and Lea Thompson.
Seeing the reunion of Doc Brown, Marty McFly and his mom, Lorraine, was exciting for Gad, and will undoubtedly be a highlight for the film's legion of devotees. However, the host had more surprise guests in store.
Gad brought on the film's co-writer, Bob Gale, and director Robert Zemeckis, who helmed the movie and co-wrote the screenplay with Gale -- a screenplay that earned both men an Oscar nomination.
"This is heavy, seeing all of you on one screen right now," Gad said. "What is it like seeing this group back together again?"
"It feels like it was just yesterday," Zemeckis said with a smile.
"It's always great to see everybody, and this is new to see everybody like this," Gale added.
The group reminisced about the production and had fun recreating some iconic moments before a few more stars dropped by, including Mary Steenburgen, who played Doc Brown's romantic interest, Clara Clayton, in Back to the Future III, and Elisabeth Shue, who played Marty's girlfriend, Jennifer, in the Back to the Future II and III.