Continuity Nod/Film

Examples of s in include:

Animated

 * At the very beginning of Madagascar: Escape 2 Africa when the animals leave Madagascar by plane the ship that the penguins stole in the first movie can be seen parked on the beach.
 * Most Pixar films use a variation of this: in most of their films, if you look very closely at the backgrounds in some scenes, there will inevitably be an element from another Pixar film hidden somewhere-not just with their past films, but also their future ones as well.

Live-Action
"Elsa: What's this? Indy: Ark of the Covenant. Elsa: Are you sure? Indy: Pretty sure."
 * From the Batman franchise: In Batman and Robin, a scene of Arkham Asylum briefly shows the outfits of the Riddler and Two-Face from Batman Forever.
 * In the second Batman film of the 90s, Batman Returns, there's a line of dialogue that refers to Vicky Vale, the Love Interest from the first film.
 * In the first Alien vs. Predator film, the expedition to Antarctica was financed by the Weyland Corporation and includes Charles Bishop Weyland himself. In Requiem, the Predator's plasma gun is turned over to the obviously very-well connected Ms. Yutani. As every fan of the Alien series knows, Weyland-Yutani was the major corporation in the background of the films, at the time of Aliens 3 led by the obviously many time great Identical Grandson of Charles Weyland and the model for the Bishop androids (with Lance Henrikson playing all three roles).
 * Every Pirates of the Caribbean movie to date has included someone's remarkable survival and escape from an isolated island being explained as "Sea turtles, mate!" Except that in two of those cases we actually know what happened, while the dog's survival into the third movie is never explained.
 * Another one comes in the second movie, when Jack Sparrow says that Will Turner has a "lovely singing voice" because he's a eunuch (he's not). This is a nod to the first movie, which had multiple jokes about Will being a eunuch.
 * Indiana Jones
 * Indiana Jones and the Last Crusade. Indy casually identifies a tomb painting of the Ark of the Covenant, as recovered by Indy in Raiders of the Lost Ark—complete with appropriate musical motif from that movie.


 * Indiana Jones and the Kingdom of the Crystal Skull is full of them. From ancient artifacts to family photos there are dozens of references to the previous movies and to when they Recycled: the Series.
 * A similar nod happens in Kingdom of the Crystal Skull, where you see the actual Ark, which has been packed up and stored in Area 51.
 * The James Bond film Die Another Day contains Shout Outs and Continuity Nods to all of the previous Bond films. Q's lab, for example, contains gadgets from a number of previous films, such as the jet pack from Thunderball and the crocodile sub from Octopussy.
 * In addition, when Q gives Bond his new watch, he says, "This will be your twentieth, I believe." Die Another Day was the 20th Bond film.
 * It also references several things in the Bond books that didn't make it into movies, such as the scene with M talking to Bond through bulletproof glass.
 * In On Her Majesty's Secret Service James Bond resigns and is cleaning out his desk. He takes out Honey Ryder's knife and belt from Dr. No, Red Grant's garrote wrist watch from From Russia with Love and the aqua breather he used in Thunderball. All this while as music from each of the previous movies are played for each item. Perhaps this was a way of establishing that the new 007, George Lazenby was the same Bond of the previous adventures where he was played by Sean Connery.
 * In a rare continuity nod for an action film, Jay in Men in Black 2 actually explains where his former partner El went before he hooks back up with Kay--apparently, she liked being a morgue worker more than an MIB. We also learn that Kay's wife left him, which not only gets her out of the way for Kay to go back to the MIB, but is also a refreshing change from the usual fare of just ignoring that the previous love interest ever existed.
 * Serenity has an extremely subtle continuity nod during Mal's Shirtless Scene, where one can see a small vertical scar on his upper right chest. This is the same scar he picked up in "The Train Job" when Crow threw a knife at him and hit him in that spot.
 * There's also a scar in the center of his chest from the torture device in "War Stories".
 * In Speed 2, a cruise liner crashes into and demolishes an expensive boat belonging to the same guy whose sports car Jack (Keanu Reeves) wrecks in pursuit of the bus in the first movie. And Alex commandeers one of the guy's smaller boats to save Annie.
 * Similar to the Batman example above, the 2007 Teenage Mutant Ninja Turtles movie had a scene near the end where Splinter had set up a trophy room. Shredder's helmet and various other artifacts from enemies of the previous three live-action films could be seen on shelves.
 * Mark from The Gamers shows up a couple of times in the second movie and makes references to it.
 * Kevin Smith's movies, particularly those set in The View Askewniverse, are full of Continuity Nods, with characters frequently making reference to events, characters, or relatives of characters that have either happened or been alluded to (or will be) in other movies.
 * The 2009 Star Trek movie features a brief reference to Admiral Archer, who keeps beagles, an obvious reference to the star of Star Trek Enterprise (and his owner, Captain Archer).
 * Also, one of the members of Kirk's disciplinary board is an Admiral Komack - which was the name of of an Admiral in TOS.
 * A lot of nods in Star Trek: during the Kobayashi Maru test, Kirk is eating an apple nonchalantly. In The Wrath of Khan, Kirk tells Saavik how he beat the test—while eating an apple.
 * Though according to the DVD commentary on the 2009 film, this parallel was unintentional.
 * There's a blink-your-ears-and-you'll-miss-it call for Nurse Chapel at one point.
 * Scotty had a pet tribble, in his Reassigned to Antarctica base.
 * For the most part, George Lucas ignores the Star Wars Expanded Universe. But Coruscant, the capital of the Old Republic, was established in The Thrawn Trilogy. The prequel trilogy continues to use Coruscant.
 * And it was retconned into the ending of episode VI, when all planets celebrating are shown (Naboo is retconned into this too, if you must know. As is Hayden Christensen as the ghost of Anakin.
 * Actually, this scene was changed twice: first for the "Special Edition" theatrical re-release, and again for the trilogy DVD release.
 * In the Special Edition of A New Hope, Dash Rendar's Outrider ship from Shadows of the Empire can be seen landing in Mos Eisley.
 * In Spider-Man 2, the staff of the Daily Bugle is trying to think of a name for the recently altered Dr. Octavius. One suggestion is Dr. Strange which is rejected as already taken, presumably by Marvel's Sorcerer Supreme.
 * The Lord of the Rings films feature several nods to other books by Tolkien (though sometimes only in the EE): the allusions are much more explicit in the books, but in the films they can be easy to miss or obscure. See for instance the trolls (from The Hobbit) which are glimpsed in FotR and Aragorn singing the Lay of Leithian (from The Silmarillion).
 * The terrorist group from the movie Iron Man is called The Ten Rings. The Mandarin, a major Iron Man villain from the comics, gets his powers from ten magical rings (though later it's retconned to be Shi'ar technology)
 * Raza, the leader of the Ten Rings, even mention "the man whose ring I wear", i.e. The Mandarin.
 * In Rocky II Rocky takes Paulie's old job at the meat packing plant. During a montage of him doing grueling, manual work there Rocky playfully hits a hanging side of beef like he did to train for his fight with Apollo in the first movie.
 * Rocky Balboa is full of these. Almost every (surviving) character who appeared in the original film (Little Marie, Duke, Spider Rico, Andy the bartender) returns. In a deleted scene (cut because of disagreements with Carl Weathers), Rocky has a photo of Apollo Creed in his house. It's mentioned in dialogue that Rocky's statue (which was unveiled in Rocky III and seen in Rocky V) was removed from its place at the Philidelphia Museum of Arts. The film opens with the song "Take You Back", which was performed in the original film by Frank Stallone. Finally, the training sequence once again has Rocky run through a Philadelphia park and up the Philadelphia Museum of Arts set of steps.
 * Airplane 2 The Sequel. While talking to Buck Murdock on the radio, Ted says "Roger, Murdock". Roger Murdock was the character in Airplane! played by Kareem Abdul-Jabar.
 * The third Mission Impossible film makes use of "The Plot," a music cue by Lalo Schifrin from the original series that is only familiar to fans.
 * The movie Predators had the female lead made a mention of the first Predator and about the story of how Arnold Schwarzenegger's character, Dutch, managed to defeat a Predator after it slaughtered his entire team.
 * In the original Halloween, Laurie mentions having a crush on one of her classmates Ben Tramer. In the sequel, the police accidentally kill a costumed teenager after mistaking him for Michael Myers. Turns out that poor teenager was Ben Tramer.
 * Quentin Tarantino's films are full of in-universe references. Characters from distinct films can be members of the same family (most famously the Vega brothers, but Donny "The Bear Jew" Donowitz from Inglorious Basterds is the father of film producer Lee Donowitz from True Romance). A particularly obscure example is found with Jules' from Pulp Fiction, who quotes the same bible verse before killing people as did the Hatori Hanzo in the Japanese TV and film series, Shadow Warriors(Kage no Gundan), which starred Sonny Chiba. Hatori Hanzo, once more played by Chiba, is the sword smith who appears in the Kill Bill films, bringing the reference back around. Indeed, the quote Jules uses is actually a retranslation from the Japanese scripts and not the version as it appears in English language editions of the bible. It can be noted that in Shadow Warriors, Chiba plays members of the same family from different generations, most of whom share the same name, with the Kill Bill character seeming to be a further descendant.
 * Several throughout the RoboCop series:
 * In Robocop 2, the titular character brings a Cobra Assault Cannon (the weapon used by Boddicker and his gang in the first film) to the final showdown with Cain, but it is swiftly rendered useless after the bullets fail to impede the killer cyborg.
 * In Robocop 3, the "I'd buy that for a dollar!" television host is seen in a brief cameo, while an OCP officer named Cecil (who attempted to stop the officers from destroying Robo in the OCP parking garage during the first film) returns as an officer who walks out on OCP and helps Sergeant Reed during the Splatterpunk attack in Old Detroit.
 * In Scream 4, a girl in the beginning gets crushed by a garage door, harkening back to a similar death from the first film.
 * In The Godfather, Enzo Aguello (a baker from Sicily) helps Michael Corleone when assassins attempt to kill Don Corleone at the hospital he's staying in, by standing guard outside the building and waiting for the police to arrive. He returns in Part III as the man who bakes a cake for Michael when he receives the Order of Saint Sebastian.
 * Two very different films are established as being in the same 'verse by one of these. In John Landis's 1978's Animal House, the "what happened to...?" epilogue states that Neidermeyer was fragged by his own troops in Vietnam. In the segment of 1983's The Twilight Zone movie that Landis directed, the focus is on a particular group of soldiers, one of whom makes an offhand comment about having "fragged Neidermeyer".