The question of how the Pearson patriarch met his demise has been one fans have obsessed over ever since the fifth episode of the first season, "The Game Plan," in which Kate reveals to Toby that she watches football every Sunday opposite her dad's ashes. That wasn't always supposed to be the case: According to Justin Hartley's interview with Vanity Fair, the cast of This Is Us nearly revealed that Milo Ventimiglia's character died right after the first episode aired.
The cast wasn't trying to be malicious — they just didn't realize that a very important part of the episode got cut out at the last minute.
In the original pilot episode (a version of the script can be found online, with the original title Thirty-Six), Randall (Sterling K. Brown) tells his biological father William (Ron Cephas Jones) that his adoptive dad Jack passed away "a few years back." It's a small line, but obviously, an important one: When Rebecca (Mandy Moore) shows up on the arm of Miguel (Jon Huertas) in the next episode, we're left wondering whether she and Jack divorced, or if Jack is no longer alive.
Clearly, no one informed the cast that Randall's line didn't make it to air, because once it came time to tweet about the pilot episode, it was spoilers city for the cast.
"[The] pilot airs, and [the cast starts] tweeting and texting all kinds of stuff about Jack’s death," Hartley told Vanity Fair. "So we get a letter from NBC like, 'Don’t talk about Jack’s death. Nobody knows he’s dead.' And we’re like, 'Yes! He said it in the pilot!' And they’re like, 'No, we took that out.' I don’t know how nobody got in trouble for that, but what are you gonna do?"
Hey, Hartley, if you've got any more spoilers — like, say, what's really up with that fire that maybe claimed Jack's life — I'm totally okay with you tweeting about it. There's only so much suspense we can take.