Mandy Moore Filming Jack's Funeral on 'This Is Us'

Mandy Moore looked mournful on the set of "This Is Us" ... just another clue of what promises to be an excruciating upcoming episode.

Mandy and some of her cast members were spotted Tuesday decked out all in black ... for what looks like the filming of a funeral. The show's special episode following the Super Bowl promises to answer questions surrounding Jack's death.

Logan Shroyer (who plays teenage Kevin) and Hannah Zeile (teenage Kate) are also decked out in black. Niles Fitch (teenage Randall) appears to be sitting passenger side.

Better have the Kleenex on standby.