In episode 13 he muses that he's a first generation Morlock since he's spending so much time underground. In Episode 48 he calls the soldiers surface dwellers as he guns them down.
In the first episode of Hells Paradise Jarid hits a Zombie with his backpack before being tackled by a different one. In the second episode, Keane notices that that particular zombie has its neck broken and asks how it was killed.
Nearby the beginning of "Strong Bad is in Jail Cartoon", Strong Sad says in a letter that he and Marzipan have a bakavla in the oven. At the end of the cartoon, Marzipan serves it to the other characters.
At the beginning of "Drive-Thru", Strong Bad is using an air compresser to launch a toy rocket to Europa, in the hopes that it'll return to Earth and bring him back some lobsters. At the end, sure enough, it falls back to Earth and cracks open, revealing a space lobster. The Drive-Thru Whale asks it to sever its leg, which it does, and the whale eats it (but not its severed leg, oddly) and flies into outer space. ...Yeah.
In sbemail #38, titled helium, we discover that Strong Mad's voice doesn't change at all when he sucks helium, to his annoyance. Exactly 114 emails later in sbemail #152, isp, we find out that Strong Bad's internet connection is so slow because Strong Mad is siphoning his bandwidth through a garden hose. Apparently bandwidth acts like "super helium" and Strong Mad finally gets his helium voice.
The short "The Luau" begins with Homestar peeing behind Marzipan's gazebo. Later on in the short, when Homestar visits Strong Bad's party, and finds out that he can't get the wood to start on fire, Homestar then asks if Strong Bad got the wood from behind the gazebo, in which Strong Bad answers "Yes, why?". Homestar then explains "Well it all started when I drank 32 glasses of melonade..."
In email #55, "cheat talk", Strong Bad waits patiently for Strong Mad (and The Cheat) to say the word "Douglas" (and jams his keyboard into Strong Sad's stomach to get him to say the word). In an Easter Egg for email #76, as Strong Bad tries to get other characters to say "Fhqwhgads", Strong Mad instead says, "DOUGLAS!", to which a surprised Strong Bad says, "Whoa! We've just had a breakthrough! You get a gold star."
In short "Play Date", Homestar calls Bubs, who tells him that he's in federal prison. However he shows up in two scenes throughout the cartoon. In the Easter Egg, Homestar asks why he's not in prison, and he says he got time out for "snitchy behavior".
In email #103, "haircut", Strong Bad, while coming up with various eyebrow-cuts for Strong Mad, randomly comes up with one looking like a character from Sweet Cuppin' Cakes, a cartoon he invented in an earlier email, whom he immediately dubs "Ready for Primetime". Fast forward to the Decemberween in July Sweet Cuppin' Cakes short; at the very, very end, guess who makes an unexpected appearance?
Near the beginning of the Strong Bad Email pet show, Strong Bad catches Homestar trying to put relish on his boots ("Homestar's always trying to give me the old relish-foot.") Near the end of the cartoon, Strong Bad and the Cheat are disqualified from the pet show not because of the cheating they actually did, but for "flagrant use of relish-foot" (the cause of which is implied to be Homestar).
In hremail7, Homestar offhandedly mentions he's contractually forbidden to even bathe in any liquid other than Melonade. At the end of the email, he walks off singing that he's going to take a bath in Melonade.
In Yu-Gi-Oh! The Abridged Series there are many of these. One starts in episode 14: Atem warns the man attacking Tea that he looks damn good in a tutu. A few years later we get episode 53. Kaiba is forced to admit it: he does look damn good in a tutu (we even get a card/photo to prove it).
In Stupid Mario Brothers "The Interactive Adventure", Luigi ended up inheriting amansion. In the first episode of Season 4 he sold it for a life supply of USB flash drives, so he could never run out of memory. In Episode 53, Mario returns after he gains his memory back, prompting Luigi to suggest a flash drive.
113. There is absolutely no need to emulate the people from Full Monty every time I hear the song "Hot Stuff".
131. No dancing in the turret. This especially applies in conjunction with rule #113.
4chan had a few people do these—one example where someone mentioned something about Code Geass, then someone posted a Slowpoke picture saying he'll respond in two years. Two years later, he responded. He has continued to do so every year on the same date since then.
The Phase novels in the Whateley Universe love the Chekhov's Gun tropes, so this pops up regularly. In the fourth Phase book, Phase considers the problems of a mutant-website-only web-spider. In the fifth book, Phase uses this as a trap. In the first Tennyo story, we learn something of her backstory, which is further fleshed out in a later Team Kimba adventure. Years later (real time), her backstory is weaponized against her in the seventh Phase story.
Contesting 8-Bit Theater for longest one ever is Red vs. Blue, with what actually happened to "poor Florida" from the first few episodes revealed at the end of Season 10, almost a decade later.
The AnimutationIrrational Exuberance starts by presenting a series of anthropomorphic fruit mascots under the slogan "Fruit Sells", such as "Rotten Apple Joe" ("Rotten Apple Computers"), "Applegrape Joe" ("Fruity Loom Incorporated"), and "Banana Joe" ("Banana Public Inc."). About halfway through, more fruit-themed mascots are presented, and the last one is..."fitness guru and short-shorts pioneer" Richard Simmons.
Captain Hammer's "Everyone's a Hero" song in Dr. Horrible's Sing-Along Blog is cut short by Dr. Horrible's Freeze Ray. Horrible goes on to sing his own song before Hammer unfreezes—and when he does, he completes the line he was in the middle of.
Captain Hammer: Everyone's a hero in their—
Hammer:[a whole song later, and after punching Horrible across the room] WAAAAAAAAAY!
Glasgow disappears at the beginning of the second Marvel arc of We Are Our Adventuring Avatars, and disappears from the plot for a while. When inside Brainiac's ship, the fate of the city becomes abundantly clear: It's part of his collection now.
At the end of the first Charlie The Unicorn video, Charlie wakes up to discover the other two unicorns have stolen his kidney. At the end of the third video, released 3 1/2 years later, Charlie wakes up to discover they've used his horn as a snowman's nose...and the snowman also has his kidney.
During the musical segment of the third video, a starfish repeatedly appears proclaiming its love for Charlie. It reappears at the climax of the fourth video to save Charlie from being blown up along with the moon.
Used at the end of Suburban Knights. At the beginning, The Nostalgia Critic rounds up everyone at his house by tricking them into thinking that they won a car. At the end, however, everyone leaves after he finds yet another thing he wants their help in looking for. The very last scene?
Also in the The Stinger, where Sci-Fi Guy is revealed to have survived...from his house being blown up 20 minutes in the movie.
What If? has a post discussing what would happen if Earth's oceans were drained through a portal to Mars. A Running Gag throughout the post is the suggestion that the Netherlands will somehow slowly take over the world. In the following post, Randall discusses what would happen to Mars. The post concludes with the Netherlands colonizing Mars as well. A few more posts down the line, we get to see what happens when gravity is misapplied to a mountain in space—it ends up impacting not Earth but Mars, AKA New Netherlands.
I'm a Marvel... and I'm a DC: At one point during the After Hours storyline, Professor Xavier mind reads Lance, Lex Luthor's L.M.D. Lance at Batman and Nick Fury's request, mentioning at one point that Lance has the Black-Eyed Peas' "My Humps" playing in the background of his head. Part 3 of the following season's Happy Hour storyline begins with a Joker-controlled Lex saying the lyrics to "My Humps" in an amusing monotone when Batman and Spider-Man attempt to interrogate him.
Early on in Return of the Cartoon Man, Peter asks Roy and Karen to "cut to the chase," and the scene immediately cuts to them chasing each other around the house. Much later, Roy interrupts Karen's exposition, looks at the camera, and says "Let's cut to the chase." The scene immediately cuts to the climactic chase sequence.
Dragon Ball Z Abridged has one where the Superfriends are talking about intervening in the plot. Off-screen, Aquaman suggests using whales. Several episodes later, Nappa "sinks" the whales, which prompts a Big "NO!" from Aquaman.
Nail and Lord Guru are introduced in a Cutaway Gag in Season 1 where Nail complains that he wishes something exciting would happen on Namek, "I don't even care what." In the next season, Frieza and his men invade Namek.
Goku charges up the spirit bomb, which draws energy from all life on the planet. Then he decides it could use a little more energy, which kills a deer and orphans its nearby child. Later, just as Vegeta is about to get nailed by it, he comments "What smells like deer?"
When Piccolo is fighting Freeza in his third form Freeza says he'll hit his glubok sooner or later. Later when he's distracting Freeza while Goku is charging his spirit bomb:
Piccolo: No no NO AUGH MY GLUBOK.
When he finds out that Gohan has stolen his dragon ball, Vegeta's scream of rage can be heard across the planet, across space, in the afterlife, and 20 years later in the Bad Future Trunks comes from. When History of Trunks: Abridged came out, that scream can be heard at the appropriate scene.
In episode 2, Piccolo comes up with a plan to defeat Raditz, but it requires Goku to distract him for five minutes. He acknowledges that Raditz was able to beat them up in less than one minute, but tells Goku "I'm sure you can handle it." In episode 29, almost four years later, Goku has a plan to defeat Freeza, and he needs Piccolo to distract him...for five minutes.
Goku: And considering how bad he was kicking my butt...ah, Iím sure you can handle it.
At the start of one episode of Endless Saturdays, Robert mentions having a webseries called Bionicle vs Transformers, which has one comment. At the end, he abandons the online news show the trio is working on to continue work on Bionicle vs Transformers, after finding out it has received another two comments.
SF Debris: during the Star Trek V: The Final Frontier review, Chuck refers to one character's field of holes in the ground as "dry ice mines", due to the smoke they emitted. About ten minutes later, another character is described thusly:
"Admiral Bob doesn't know his ass from a dry ice mine."
raocow keeps meeting old and beloved bosses from his earlier videos in the newer hacks he plays, specially Black Plague (a hilariously ugly Big Boo) and the Key Boss (a broken leftover). In some cases, their comebacks happen over half a decade after their original appearances.
In "Toys R' Us", Tyler kept telling customers that whatever they were looking for was in aisle 12B. While the narrator mentions that he sucked at assembling bikes, there is a clip of a girl riding one of his bikes, only to lose a wheel and explode into several pieces. When he was released after Christmas season, a customer asked about where he could go to talk about a bike that caused his daughter to explode. Tyler told him "Aisle 12B".
In "Neighborhood Argument"...
Tyler: Oh my God. Michael, you are a fucktard...Jesus. Michael: Don't call me "fucktard Jesus"! Tyler:[confused] I didn't call you a "fucktard Jesus".
Later on, at the dream fight, there's a sign that says "Go Fucktard Jesus!"
Early in Season 10 of Camp Should-A-Been, the counselors hold the entire semifinals in four minutes (parodying American Idol's new one-week semifinals format) and mention wanting to get back to the Rec Cabin to catch the Phillies game on ESPN-HD. The following season, an on-going gimmick was that anyone who mentioned Adele got hit with a tranquilizer dart, and the counselors themselves get tranq'd at the end, as they say they're ready to catch their plane back to Philadelphia.
In the 10000 views celebration of The Most Stupid Deaths In Super Mario 64, Clone 4 says, in relation to their fight on Hyrule Castle, that if Link notices anything, they'll just leave a note blaming Clone 2. In the 20000 view celebration episode, Link finds Clone 2 and fights him for it.
While driving away from Hol Horse and J. Geil in Vaguely Recalling JoJo, Kakyoin mispronounces the name of Polnareff's deceased sister (i.e. Sherry) as Cherry. Shortly after running into Judgement several episodes later, he encounters his sister's cannibalistic doppelgänger who is actually named Cherry.
''The Gaston Trilogy: One of the villagers with a facial structure similar to Aladdin's genie turns blue and says "Phenomenal!" when Lefou dies the first time in "Gaston Plays Lefou's Quest IV." He does the same thing at the end of The Stinger of the next video.
Random Assault: Sometimes the hosts will have well-timed repeats of earlier jokes.
Rooster Teeth has a pair of RT shorts released years apart, namely Pongo and Home for the Holidays, where a joke is set up and seemingly paid off in the original short and then, years later, is paid off for real when Joel discovers the identity of his girlfriend's adopted sibling.
In "Chef Pee Pee's Clone", after Chef Pee Pee gets out of the bathroom, he says, "I took an opposite of a Chef Pee Pee in there! They should call me Chef Poo Poo!". Guess what Junior names Chef Pee Pee's clone at the end of the video.
In "Black Yoshi's Girlfriend Problem!", after Delilah breaks up with Black Yoshi, she hooks up with Popeye, who tries to open up a can of spinach so he can beat up Black Yoshi. Unfortunately, he can't get the can open. At the end of the episode, Popeye returns, revealing he finally got the can open.
In "Cody the Magician!", Bowser Junior shoves the 6 of Clubs card up his ass when Cody tells him to do it. Later in the episode, when Cody's Ken doll does his escape artist trick, the card that was previously in Junior's ass appears in the tank, in Ken's place.