Host Jimmy Fallon brought up things that usually go wrong during a live production...
...but little did he know, Krasinski had a slightly embarrassing story to tell about something that happened to him during a recent performance.
He didn't realize until later that he'd been acting while his pants were unzipped.
But at least Krasinski had a good sense of humor about the absolutely mortifying situation.
Sounds like it was an eye-opening experience for play attendees.