Mandy Moore's acting career went very low key after the flop of License to Wed, as she again focused more on her singing with only Tangled getting her noticed again, until she considered retiring from it. Then her performance on this show received a ton of praise and got a lot of speculation going on how she could build off it.
Milo Ventimiglia, to a lesser extent. After Heroes ended, the only high-profile thing he did after that was a supporting role in the reviled Adam Sandler comedy That's My Boy. Ventimiglia stuck to doing some low-profile work in indie movies and appeared in some short-lived TV series before This is Us made him a star again.
Deleted Scene: Just a few days before "The 20's" aired came Anthony Rapp's accusations that Kevin Spacey had molested him at a party, causing the crew to hastily cut a scene where Kevin's roommate offers to take him to a party at Spacey's.
Apparently the crew seems to think that Canada exists in a bubble since the scene was left intact for the Canadian airing.
Blind theater actor Blake Stadnik makes his onscreen acting debut as the blind character Jack Damon. Though unlike the character, he had six years of sight rather than being blind from birth.
Timothy Omundson, who two years earlier suffered a stroke that physically affected him so much that he now refers to himself as "Timothy 2.0," has his first acting role since it happened as a man who similarly has just recently started to recover from a devastating stroke.
Dyeing for Your Art: Before the show premiered, Milo Ventimiglia was sporting a thick mustache and long hair, which had a lot of media outlets puzzled until the pilot premiered and revealed that because Jack is from the 1970s and 1980s, the shaggy hair and mustache is period appropriate. As he joked to Chelsea Handler:
Milo: [Dan Fogelman] walked around, asking every female in the office if she liked it or didn't like it in more explicit terms. Chelsea: You can use those terms. Milo: "Do you want to fuck Milo, yes?" or "Do you want to fuck Milo, no?" And it was split right down the middle!
Enforced Method Acting: In a deleted or hidden video clip on Entertainment Weekly's website, Milo said he had to change the babies' diapers for real while filming because they really did need their diapers changed.
While most viewers didn't recognize the twist ending, some more Genre Savvy viewers were able to figure out that Randall had to be somehow related to the others because of the whole birthday concept and the fact that he's the only main character of color among the predominantly white cast. It's the fact that Jack and Rebecca are their parents and lived during a different time period that caught everyone.
After the Wham Shot of Miguel and Rebecca, most viewers were already guessing that Jack was dead, especially after a line William said in the pilot appeared to have referenced Jack in the past tense. Episode 5 confirmed that he did pass away and Kate keeps his ashes on her mantle.
Quite a few fans called that the reason Kate blames herself for her fathers death was because he stayed in the burning house to save her dog rather than escaping with the others.
Meaningful Release Date: The episode "Super Bowl Sunday" premiered on a Super Bowl Sunday, specifically Super Bowl LII.
Additionally, footage from the actual game can be seen playing on the TV in the background during one scene.
Meta Casting: The singer Rebecca is played by an actual Idol Singer and the actor Kevin is obviously played by an actual actor.
Taken Up to Eleven with Jack Damon being played by a real blind singer (though in musical theater rather than pop music).
Unintentional Period Piece: Has a very strong potential to become one in the future. Fitbits, iPhones, and Macbooks are omnipresent in the show, and there are plenty of pop culture references sprinkled into the dialogue.
Dan Fogelman stated that while Kate followed Kevin to Los Angeles as he pursued his acting career, Randall stayed behind on the East Coast to stay close to their parents.
Sterling K. Brown, who plays Randall, implies that Jack died when the kids were relatively young and it's part of the reason Randall tries to find his biological father. Possibly foreshadowed by Kate's line in the pilot "You remember what Dad used to say?"Confirmed in episode 5 when Kate shows Toby the urn of his ashes.
At the start of Season 4, Fogelman specified that the Jack Damon storyline takes place twelve years after the future scenes in the previous two seasons.