Chris Sullivan Filmed 'This Is Us' Wedding With Food Poisoning

While Kate and Toby's wedding may have looked like a dream on the season 2 finale of This Is Us, Chris Sullivan's version of the experience was anything but.

"At my real wedding, I wore traditional Celtic garb — a kilt. At Kate and Toby's wedding I had bad food poisoning," Sullivan told Jimmy Fallon on The Tonight Show.

The 37-year-old actor, who has been married to short-film producer Rachel Reichard for six years, didn't hint at what caused the sickness, but did say there was "some sweating" and heavy breathing.

The NBC hit drama wrapped its sophomore season with another touching episode involving not only ever single member of the Pearson family (yes, even Jack), but Toby's parents as well.

Before Sullivan's Toby Damon and Chrissy Metz's Kate Pearson finally said their vows, Kate went missing the day of the wedding, not picking up any phone calls. Later, she revealed to Rebecca (Mandy Moore) that she'd been having recurring dreams in which Jack (Milo Ventimiglia) was still alive and that instead of the special day being her and Toby's wedding, it was Rebecca and Jack's vow renewal ceremony.

During the heartbreaking scenes, Jack talks about opening the construction company, Big Three Homes, that he always dreamed of opening as his kids were growing up. Jack reveals that his wife helped him open the company and turned it into a massive success.

The episode also showed a reception for the renewal ceremony, where member of the Pearson family danced and laughed. And in one heartwarming scene, Rebecca sings a moving rendition of "Moonshadow," Jack and Rebecca's song.

Fans will remember Rebecca motivating Jack to open the company, and volunteering herself to help the day of the fire that ultimately took Jack's life.

While Kate was MIA from the wedding festivities, Toby's parents, played by Wendie Malick and Wonder Years alum Dan Lauria, warned Toby against marrying Kate, who they said was "unstable."

Toby's parents also said Kate also has a lot of "issues" and pointed out how he unconditionally dotes on her like he used to with his ex-wife Josie. His parents reveal that he gave so much to Josie that he lost himself in the process and became clinically depressed. But he defends Kate, assuring them that this relationship is different, and dismisses his parents from the room.

But the finale wasn't all conflict resolution and fairy tale alternative ending; it also left fans with quite a few shockers — including a series of glimpses into the future that fans found unsettling. Read more about that here and here.

This Is Us will return for season three in fall of 2018.