Matt Damon and David Letterman made a surprise joint appearance in the fourth-season premiere of The Gilded Age, which aired Sunday, November 1. The pair can be seen walking across the New York City street where the drama’s central families, the Russells and the Van Rhijns, live.

The cameo reportedly came about through Letterman’s long-standing interest in appearing as a background actor. Isabel Richardson, showrunner of My Next Guest Needs No Introduction With David Letterman, told Vulture that he had been inspired by Gary Mule Deer’s brief appearance in Annie Hall and had previously pursued cameo opportunities in several other productions without success.

The connection with Damon emerged while Letterman’s team was researching the actor for an upcoming episode. They learned that Damon had started his career doing background work, leading the team to propose a cameo in The Gilded Age. Richardson said Damon selected the idea as his favorite from a list of possible segments for his episode.

A line producer from Letterman’s show passed the proposal to someone working on the HBO drama, and the idea eventually reached executive producer Kate Churchill. The cameo was approved by creator Julian Fellowes and HBO, with the scene filmed on a closed set.

Richardson and Churchill recalled that Letterman was initially apprehensive about the costumes but became enthusiastic once filming began. Churchill described him as highly curious and excited on set, while Richardson said Damon laughed throughout the day and had to hold onto his mustache when it began to loosen.

The Gilded Age airs Sundays at 9 p.m. on HBO and HBO Max.

Sources: Us Weekly.