1. In the episode of The Office where Michael justifies spending $80 worth of magic equipment on the corporate credit card, he can be seen wearing a thumb tip — a magic prop used to conceal small objects.
2. In the pilot episode of Futurama, Bender makes a suggestion to hide in the museum because it's "free on Tuesdays." Checking a calendar for 2099 reveals that 31 December does indeed fall on a Tuesday.
3. In the scene from Breaking Bad where Hank is told his wife's been in a serious car accident, the saturation levels are intentionally low to illustrate his dread. When he realises he's been fooled, the levels progressively fade back to normal as his rage hits.
4. When Marshall and Lily are discussing what to name their baby in season six of How I Met Your Mother, there's a genius callback to the first ever episode.
5. Danerys' braids increase in number and intricacy with each victory she achieves in Game of Thrones.
6. Captain Holt in Brooklyn Nine Nine wears a "WTC" breast bar, indicating that he was working on 9/11.
7. In The Good Place, there's a magazine advert for champagne named after Jean-Ralphio from Parks and Recreation.
8. And we also see that Parks and Recreation's resident perfume artist, Dennis Feinstein exists in the world of The Good Place too.
9. After the plane crash in the season two finale of Breaking Bad, ABQ residents briefly wear commemorative ribbons. Saul, however, keeps his ribbon on long after the crash, indicating his dedication to using the incident to score lawsuits.
10. In season two of Frasier, he recalls a school bully shoving him into a locker while he was wearing a girls' field hockey uniform. Nine seasons later, Niles mentions that Frasier accidentally joined the girls' field hockey team, which explains why he was wearing the uniform.
11. When Dwight becomes acting manager in The Office, Andy starts wearing short sleeved shirts, continuing his strategy of "personality mirroring" in a bid to become his number two.
12. In the SpongeBob SquarePants episode, "Dying For Pie," SpongeBob slides across the window in order to follow Squidward. In doing so, he unintentionally "cleans" the window on account of being a sponge.
13. And Plankton has holographic meatloaf for dinner because holograms are projections of light, and plankton gain energy from photosynthesis.
14. In the second season of The Walking Dead, Daryl retrieves a bag of drugs from his brother's motorcycle. He says it contains "crystal, ecstasy, painkillers and doxycycline." The "crystal" he refers to are the blue fragments at the bottom of the bag — a correct timeline shout out to Breaking Bad's blue meth.
15. In season two of The Office, Ryan says Jim eats a ham and cheese sandwich every day. In season three, however, Jim says he ate a tuna sandwich at his first day at Stanford, which implies he was trying to reinvent himself at his new job.
16. In the Scrubs episode, "My Screw Up," Ben tells Dr Cox that he'll carry his camera with him until "the day he dies." After J.D tells Dr Cox that a patient has passed away, Ben is without his camera for the rest of the episode, indicating that he's the patient who died long before it's confirmed.
17. In season seven of It's Always Sunny In Philadelphia, Charlie and Dennis discuss the dangers of telling random strangers in bars to be quiet. Dennis says that he could be someone with "duct tape and zip ties" in the trunk of their car. Five episodes later, it's revealed that he has such tools in his own trunk.
18. In season six of How I Met Your Mother, Lily believes she's pregnant. When she announces it to the group, they propose a toast to her and Marshall. However, refraining from consuming alcohol, Lily joins in the toast by holding up an empty hand.
19. At the start of season five in Friends, the guys reminisce about a beer they loved during their time in London. By episode 20, we see that Joey has gone out and bought some.
20. In the "Playtest" episode of Black Mirror, there's a contract containing the line: "If you have paused to read this, you will die unless you forward it onto five people within a 28 day period."
21. In season three of Daredevil, a poster is visible in the background of the boxing gym advertising a fight between Parker and Morales — a nod to Spider-Man.
22. In That 70s Show, Eric celebrates his 18th birthday by drinking beer. This was in keeping with the fact that between the years 1969-1976, 30 US states lowered their alcohol purchase ages from 21 to 18.
23. In season one of Friends, Chandler tries to convince Rachel to change the channel by telling her Weekend at Bernie's is on. In season four, the movie is revealed to be Rachel's secret favourite during the trivia quiz.
24. In the opening sequence of Family Guy, Lois looks at the actual sheet music for the theme song.
25. In the It's Always Sunny in Philadelphia episode "The Gang Gets Trapped," it seems that the group bought an Indiana Jones costume before breaking into the house, but couldn't decide who should wear it. Instead, they split it up — Charlie can be seen wearing the jacket, Mac the hat and Frank the whip.
26. In the "Weight Loss" episode of The Office, the Scranton branch loses the competition by just 4lbs. However, Jim shows up to the final weigh-in soaking wet. A quick Google search reveals that wet hair and clothes add around 5lbs to a person's weight.
27. And, finally, The Walking Dead title sequence becomes more decayed with each season.