Ventimiglia, 39, noticed and got together his cast members and crew to film the big moment.
“This family is actually watching our show. We’re filming next door. We’re going to go knock on their door. Come on!” the actor said, setting up the scene before he ran over to the glass door.
Of course, no surprise would be complete without selfies for posterity, and Ventimiglia, as well as the teenage versions of The Big Three -- Hannah Zeile (Kate), Logan Shroyer (Kevin) and Niles Fitch (Randall) -- gathered to take a few snaps with Fred.
This Is Us
star Justin Hartley,
who plays adult Kevin, opened up to ET
about what’s to come for the remaining five episodes of the season.
“It may take a dark turn, so get ready for that. It gets real,” Hartley warns.
This Is Us airs Tuesdays at 9 p.m. ET/PT on NBC.