The trivia items below may give away important plot points.
Sylvester Stallone appears in the second season as himself and Kate tells him that her father (played by Milo Ventimiglia) has seen every Rocky movie. This is ironic because Milo Ventimiglia actually played Rocky Balboa's son.
There are a few hints in the pilot that Kevin and Kate are twins and that Randall is their brother. For example, in the scene where Randall gets an email saying that they found his biological father, an email entitled "It's Our Birthday Bro" can be seen in his inbox from Kevin.
A persistent theme in the storylines about Randall's childhood is the fact that despite their best intentions and love for their son, Jack and Rebecca Pearson repeatedly show that they are naive and ill-prepared for the realities of raising a black child. As several TV writers (such as Jezebel's Kara Brown, Hypable's Tariq Kyle, and The Medium Is Not Enough's Rob Buckley) noted, one of the more subtle examples of the Pearsons' obliviousness on this matter is that until they changed his name from Kyle to Randall, they had given their three children names that all started with Ks, meaning that together their children's initials were KKK.