Warning: Spoilers ahead for all three seasons of The Umbrella Academy.
1. When Viktor looks at the back cover of his memoir in the very first episode of the series, you can spot a blurb from none other than the My Chemical Romance frontman Gerard Way, who wrote the comics on which the series is based. He calls the book "an incredible read."
2. Speaking of Viktor's memoir: During the montage of all the siblings reading it, you can see that Luther's copy is covered in notes.
3. There's a hint that Reginald is lying about Viktor's lack of powers in the very first episode: Despite his apparent ordinariness, Reginald monitors Viktor the same way he does the other children, and when his image appears onscreen, you can hear some kind of monitor beeping faster and more loudly for Viktor than it does for the other children.
4. Luther, who Reginald banished to the moon on a pointless mission for four years, apparently hung photos of the moon on his bedroom walls as a child.
5. In the pilot, Viktor reminisces with Pogo about making his missing brother Five peanut butter and marshmallow sandwiches every night while he was gone, in the hopes that he would come back and have something to eat if he was hungry.
Later on in that episode, Five does return, and the first thing he does is make himself a peanut butter and marshmallow sandwich.
6. Ben, the deceased Hargreeves sibling, appears as a ghost to Klaus, who is able to see and interact with the dead. But Klaus uses drugs and alcohol to blunt his power, since his sobriety results in an endless stream of ghosts tormenting him. Therefore, when we first see Ben, and Klaus is, as per usual, intoxicated, Ben is wearing a hood, and his eyes remain closed for the most part.
Later on, when Klaus wakes up after a bender, Ben is more present, in that he can read and speak to Klaus clearly. But his hood remains up.
And when Klaus is kidnapped and unable to access drugs or alcohol, Ben's hood comes down, since his brother is finally (and unwillingly) sober.
7. Out of all the siblings, Diego is closest with their robot mother, Grace. When Luther looks at Diego's otherwise Spartan apartment while he's out, he spots one homey touch: a framed piece of needlepoint, presumably the work of Grace.
8. If the motel where Hazel drives his girlfriend Agnes looked familiar to you, that's because it's one and the same as the Rosebud Motel in Schitt's Creek.
9. When the family meets at a bowling alley during the Season 1 finale, they sign up for their lane under the name "Umbrella Team."
10. Right before Diego powers her down, Grace is embroidering an image of the moon breaking into chunks...
...which is what nearly ends the world in the season finale.
11. In the poster for Season 2, the reflections in the family's glasses hint at their respective plot lines for the season. For instance, you can see Lila in Diego's glasses, a civil rights protest in Allison's, and cult members in Klaus's.
12. When Luther farts in the elevator, you can spot David Castañeda (Diego) laughing in the background.
13. Justin H. Min (Ben) told TV Guide that getting Sparrow Ben's hair just right involved trying out "around 20 iterations," and added that though you can't really see them, there are some dyed blue streaks in it.
14. In the same video, Min said that originally, Klaus was going to be the first one to see Ben and say his name. But this ended up getting changed to all the siblings saying "shit" in unison, to prevent the audience from being confused about if Ben was really alive or not, since Klaus being able to see him wouldn't be out of the ordinary.
15. In Season 2, Five breaks a vending machine in a fit of rage after his Fudge Nutter gets stuck. In a Reddit AMA, series creator Steve Blackman explained that this was not a random instance of extreme hanger.
Blackman wrote, "That's a callback to season one. If you recall, that's the chocolate The Handler offered Five in her office."
16. In the same Reddit AMA, Blackman revealed that in a bit of subliminal foreshadowing, there are 43 sparrows hidden through Season 2. For instance, when Harlan tests his telekinesis in the season finale, the toy he makes float is a wooden sparrow.
17. During the group dance sequence that kicked off Season 1, one of Luther's moves is a "crab dance."
Two seasons later, he's back at it during the "Footloose" dance-off between the Umbrella and Sparrow Academies. Since this routine is Diego's hallucination, and he wasn't there while Luther was dancing alone in his room in Season 1, I like to think that Luther's done the crab dance on many occasions, to the point where Diego associates him with it.
18. Justin H. Min and David Castañeda told Newsweek that they improvised the scene from the eighth episode of Season 3 where Ben and Diego start arguing in Korean and Spanish, respectively. It was Castañeda's idea, and Min said they were "shocked" that it made it into the final version of the episode.
19. In Season 3, Klaus discovers that he has the power of immortality, and announces it to his makeshift family of dysfunctional superheroes like this.
And, about a decade ago, in another show about a makeshift family of dysfunctional superheroes called Misfits, another irreverent, immortal character played by Robert Sheehan made nearly the exact same proclamation.
20. The cup Stanley is drinking from before he is killed by the Kugelblitz has the version of Diego from the comics printed on it.
21. And finally: With the exception of Viktor, all the Hargreeves siblings received umbrella tattoos on their wrists during childhood. But after the universe is reset at the end of Season 3, those tattoos, along with the siblings' powers, are missing.
Number Five even checks for his and can't find it.
