There is a moment during Mission 14, "Virtuous Circle" where the mission becomes hilarious and never stops being hilarious. It's when Maxine comes out as a Dungeons & Dragons player. It only becomes funnier when Sam Yao and her begin planning their next game. That you are being chased by zombies to obtain their D&D supplies only makes it funnier.
During the same mission: Sam: "Who knows, maybe they will make a game of the zombie apocalypse!" Maxine: "Don't be ridiculous!"
The radio broadcasts.
One in particular has someone commenting on an influx of sport bras being brought in. Eugene and Jack further add that one runner specifically seems to have a fixation on them: you.
There's one broadcast when Jack and Eugene explain ROFFLENET, and they do it like a sort of cheesy infomercial. "What is it, Eugene?" "Well, gee, I'll tell ya, Jack!" By the end of it, Jack has begun saying things like "Golly, mister!", laughing almost too hard to say anything, while Eugene (also laughing) pleads for him to stop.
Another funny thing about Radio Abel is the interaction between Jack and Eugene. Usually, Eugene is the Straight Man to Jack's Wise Guy, with Jack making silly, often painfully awful jokes (Zombie stand-up...) and Eugene nipping the worse stuff in the bud. But this dynamic switches when something... conspiracy-theory-ish comes into play. Eugene's favorite person to listen to on the radio is Father Michael, a paranoid Scottish holy man who rambles into the air waves about how the whole apocalypse is a pre-planned zombie conspiracy. Eugene doesn't believe it, but he finds it amusing all the same. Jack thinks Father Michael is creepy. And when a caller with an obnoxiously thick hill billy accent comes on and mentions that he thinks it's all a conspiracy to steal people's guns, and that zombies see via heat and that the best way to hide from them is to cover yourself in cold mud, Eugene states emphatically that the call in question is his favorite so far. Jack has to tell the listeners in no uncertain terms that covering yourself in mud will not save you from zombies, while Eugene tries to convince Jack that it might be true.
Naomi Alderman makes a cameo as a businesswoman describing her first encounter with a zombie. The story culminates with her writing out a bullet-point list of all the reasons she and her colleagues should leave the room with the newly-turned zombie. Said reasons include "he's a zombie", "even if he wasn't a zombie he's still trying to bite people", "look how he doesn't react if I hit him with a chair" and "if we get infected, imagine how business productivity will drop".
In the downloadable PDF handbook, Chris McShell is titled in the Runner's Roster as the "BAMF statician."
In the fourth side mission of Season 2, Janine De Luca mentions that they've had a few zombie celebrity sightings, including "the zombified members of One Direction. Ironically, they were all shambling in different directions."
In the 5K trainer, the incredibly meek and quiet Dr. Myers at one point imitates a zombie as a way of trying to motivate you. It's the cutest, most adorable zombie gurgle ever.
Near the beginning of Mission 13, Dr. Myers scolds Sam for ogling the photo of a woman in the Pandora Haze patient files... until she sees the picture herself and has the same reaction.
Bowie knife:This knife is sharper than a Cactus and more dangerous than Breaking Glass. Cut yourself on this and you’ll Scream Like A Baby. Wield it well, however, and you’ll be Heroes. For now, though, it’s probably best you Play It Safe and keep it sheathed. At least until you’re feeling Under Pressure by an approaching Dead Man Walking. Just one bite is all it takes, and then it’s Ashes To Ashes. And Without You I’m Nothing. …Ziggy Stardust.