Crossover Punchline

Unlike a regular television Crossover, the Crossover Punchline is a last-minute gag at the end of an episode. The Crossover is not vital to the storyline, it's just there for the fun of it. Used for laughs, it generally also uses the tropes All Just a Dream or Alternate Universe.

Anime

 * Project A-ko featured a blink-and-you'll-miss-it gag at the end of the original OAV, where A-Ko's mother is seen sewing something that looked suspiciously like Superman's costume. The gag (that A-Ko is Superman and Wonder Woman's daughter) is made far more explicit in the Antarctic Press adaptation, where her parents refer to each other as "Clark" and "Diana."
 * An even quicker reference suggests that Gadgeteer Genius antagonist B-Ko is Tony Stark's daughter.

Comic Books
"Gadget: No. No, you cannot."
 * An issue of the Darkwing Duck comic had Launchpad lament the lack of openings for pilot/sidekicks. We then cut to him insisting he can fly the Rescue Rangers' plane. While holding it in his hand.


 * Didn't happen at the end, but the entire point for a Star Trek: The Original Series/X-Men crossover seemed to revolve around Nurse Chapel asking for Dr. McCoy, to which both Bones and Beast turn and say "Yes?", then react with mutual surprise.

Film

 * Older Than Television: at the very end of the Bob Hope film The Princess and the Pirate Bob thinks he's won the girl, only for her to rush past him and into the arms of his Road Picture co-star Bing Crosby, who had not been in the picture heretofore.
 * At the end of My Favorite Brunette, Hope's character is given a last-minute reprieve from execution; Crosby plays the very disappointed prison guard who was going to throw the switch on the electric chair.
 * Wayne's World. "Have you seen this boy?"

Live Action Television

 * The epilogue of the series finale of Newhart had Bob Newhart waking up in bed on the set of The Bob Newhart Show, next to his wife of the latter series, Suzanne Pleshette, explaining about his nightmare of being an innkeeper.
 * The final show of Noel's House Party ended with Noel waking up on the set of his earlier show Swap Shop.
 * An episode of Caroline in The City ends with Niles and Daphne of Frasier arguing over whether or not the most recent strip is funny.
 * The Seinfeld episode "The Keys" ends with Kramer appearing on Murphy Brown.
 * After the credits of one episode of Mr. Show, a comic is seen talking to Dr. Katz. Especially weird just because Mr Show is live-action.
 * One Halloween episode of Boy Meets World had a witch who wanted to sacrifice the guys in an occult ritual. At the end of the episode, they discuss the incident with another girl: Sabrina the Teenage Witch.
 * A Halloween episode of Two Guys, a Girl And A Pizza Place revealed the killer that had been going around offing the cast to be... Mimi from The Drew Carey Show, who said she wanted her own time slot.
 * An episode of The Lucy Show had Lucy mistakenly drafted into the marines, driving her drill sergeant insane. When she finally is able to leave, the sergeant is relieved he'll never have to deal with someone as nutty as her ever again. Enter her replacement...Gomer Pyle.
 * In an episode of Family Matters, Richie has a friend over that says Carl does look like the Dad from Fresh Prince! During the credits, an outtake of this scene was shown. When Richie's friend says line this time, James Avery enters to everyone's amusement (though aired on different networks, both shows are Warner Bros properties).
 * In the final episode of Coach, Hayden and Christine find that Larry, Darryl, and Darryl from Newhart have been watching their cabin after they left for Orlando. This also doubles as an in-joke, because both shows were created by Barry Kemp.

Newspaper Comics

 * The October 31, 2010 strip for BC has The Fat Broad running a pumpkin pie stand. The Cute Chick asks her where she found enough pumpkins to make the pies. The Fat Broad says that she just found one really big pumpkin. Cut to Linus, Sally, and Charlie Brown in a pumpkin patch with Charlie Brown saying "I don't think he's coming, dude."
 * One of Garfield's "I hate Mondays" gags was prompted by seeing Snoopy's reflection in the mirror.
 * References to Family Circus characters are a Running Gag in Pearls Before Swine.
 * 1997 was the year of the Great April Fools' Day Comics Switcheroonie, in which a number of comic strip writers and artists handled each other's strips as a massive practical joke. In several cases characters from different strips met, such as Garfield and Jon having their house painted and leaving to visit the Bumsteads.

Video Games

 * One of the six non-canon endings of the last episode of Red vs. Blue showed that the whole series was just an overly long Halo 2 multiplayer match.
 * The Simpsons video game has one of the last boss fights against Matt Groening—who attacks you with the main cast of Futurama.
 * And Zoidberg.

Web Comics

 * The webcomic The KAMics has done this once or twice.

Web Original

 * An episode of Yu-Gi-Oh the Abridged Series featured Ghost Nappa from Dragon Ball Abridged appearing in the middle and the Stinger. A special episode revealed that Kaiba was
 * An episode of Naruto the Abridged Series ended with the Hokage's funeral, and one of the character telling Konohamaru that he's in a better place.
 * The episode of Dragon Ball Abridged that abridged the entire first season of the abridged series (Yikes!) features Yami Yugi from Yu-Gi-Oh the Abridged Series watching the episode and pondering "This has...how many subscribers?"

Western Animation
"Peter/Hank: Hah Hah. Propane."
 * The epilogue of the The Grim Adventures of Billy and Mandy episode "My Fair Mandy", wherein Mandy enters a child beauty pageant in order to show up her arch-rival Mindy, and is coached that she would win if she would simply smile. With great effort, Mandy begins to smile, and reality shatters, placing Billy, Mandy and Grim in Townsville as distorted Powerpuff Girls. There were also several cameo from Hector Con Carne, of the show they shared a Three Shorts show with, once saying, "I'm not even supposed to be on this stupid show anymore!"
 * They once had a Dream Within a Dream within a dream within a dream within Wilt's head
 * The ending of the Sealab 2021 episode "Murphy Murph and the Feng Shui Bunch" revealed that the events of the episode were part of a video game being played by Meatwad and Master Shake of Aqua Teen Hunger Force. ("You hang windchimes for an hour, and then you fight? I don't get it.") The "Bebop Cola" episode ends to reveal the entire cartoon was a proposed cola commercial being pitched to the company execs (one played by Murphy's voice actor, the late Harry Goz) by a pair of live-action salesmen.
 * The ending of the Family Guy episode "Da Boom" has it be All Just a Dream by Pam Ewing of Dallas, who finds her husband Bobby in the shower, in a parody of the famous reveal.
 * Much later, in the fourth season, the main plot is a parody of Poltergeist has Peter replicating the scene where he pulls the skin off his face while looking in the mirror, but when it all comes off, he has turned into Hank Hill:

"Peter (looks down at Homer): Who the hell is that?"
 * on the fifth season finale "Meet The Quagmires", after Peter apparently fixes every problem from his screwing with the time-line, Roger the Alien from American Dad suddenly appears.
 * Then in "Lois Kills Stewie" (which was just a simulation) Stewie breaks into the CIA and is confronted by Bullock and Stan who Stewie mistakenly calls "Joe", lampshading how Stan is mostly an unparalyzed and neurotic version of Joe Swanson.
 * During a Police Squad! spoof you get a Jaws First Person Perspective of Stewie running down Homer Simpson as he parks in the garage.

"Stan: STOP PRETENDING I DON'T EXIST."
 * There's also an episode that has a miniature Marge appear at the bottom of the screen and at first, it seems like one of Fox's advertisements... until a miniature Quagmire attempts to rape her.
 * In the episode "The Splendid Source", Peter and his friends are going around the country questioning people about where they heard a particular joke. At one point we see them asking Bender from Futurama. They even mention that he's from Futurama.
 * Homer Simpson appeared at the end of one episode of Duckman.
 * The Simpsons has several examples:
 * Although it doesn't occur at the end, the cameo appearance of the King of the Hill cast in the "Bart Star" episode of The Simpsons probably qualifies. (Hank then proceeds to complain about the game not being worth driving 2000 miles for, if you look closely, Dale and Boomhauer can be seen in the stands as well.)
 * As might the throwaway gag of the Archie gang throwing Homer out of a van and warning him to "stay out of Riverdale." He is later seen reading an Archie comic and muttering under his breath about "stuckup Riverdale punks"
 * In a Treehouse of Horror episode, Homer makes multiple clones of himself. Amongst the clones, Peter Griffin from Family Guy can be seen.
 * Which is also a delicious Take That.
 * In another episode, Futuredrama, Bender from Futurama appears next to Bart and Homer after they travel through a time tunnel. Homer quickly proceeds to tell him to "get lost" and chucks him out of a moving vehicle.
 * These would be either shout outs.
 * In one Treehouse of Horror wherein Homer travels through time, Kang and Kodos turn into Mr. Peabody and Sherman from Rocky and Bullwinkle after saying that the Puny Earthling was unprepared for the effects of time travel. Doubles as a Brick Joke because they were seen near the beginning of the short correcting Homer saying he was the first non-Brazilian person to travel through time.
 * One episode of Chowder has a character waiting for a blind date. In walks Sara Bellum from The Powerpuff Girls—but she's not his date.
 * An episode of American Dad featured Stan name his top ten favorite fictional dogs. The #1 spot belongs to Brian from Family Guy who appears and doesn't know who Stan is.


 * In another episode Francine took an online pregnancy test from "Dr. Vadgers" which was considered a scam. The end of the episode shows Dr. Vadgers computer screen when he is then shown and revealed to be Quagmire.
 * At the end of Finding Nemo we see Mike Wazowski swimming through the end credits.
 * An episode of Time Squad had Buck and Larry believing Otto had abandoned him and trying out several replacement orphans...including Dexter, who protests he's not an orphan.
 * House of Mouse had one in its first episode. With Pepper Ann of all shows!