Amusement Park of Doom: Every incarnation has at least one of these. One of the earlier examples had a runaway robot mess with the controls. The Thirteen Ghosts of Scooby Doo, had one of the titular villains run one of these.
Animated Actors: In the 1979 prime-time special Scooby Goes Hollywood, Scooby and Shaggy get sick of their secondary roles in a formula-driven Saturday morning show, and attempt to sell a network executive on giving them a prime-time series of their own. (They pitch a number of pilot shows, all parodies of then-popular series, such as Charlie's Angels, Happy Days and The Love Boat.)
Anthropomorphic Shift: Scooby himself was suffering this by the mid-80s. He was seen walking on two legs all the time (it didn't help that his four legged design was not changed) and he was becoming somewhat less of a Speech-Impaired Animal. It seems to have been reversed beginning with A Pup Named Scooby-Doo where he became more of a quadruped again.
When Scooby runs in the early series, his legs don't follow a normal dog's running pattern. Each pair of legs go alternately in a circular motion. The only episode showing him running like a normal dog was "Decoy for a Dognapper," as he and the freed kidnapped dogs run after their captor.
Bad Future: From The 13 Ghosts of Scooby-Doo, "It's a Wonderful Scoob." Without Scooby around, the world falls to the ghosts, Daphne is a broken slave to the Time-Slime ghost, Scrappy and Flim-Flam have become his loyal servants, and Shaggy is a lone rebel that has gone crazy, adamantly believing that Scooby will return and save them.
Big Damn Movie: The supernatural will inevitably turn out to be real in a Scooby-Doo movie, but the basic formula is usually the same.
Not necessarily. Where's My Mummy? had a Scooby-Doo Hoax, albeit a very elaborate one put on by Velma, an archaeologist, and an Ardeth Bay expy. Which none of them ever think to tell the rest of the Scoobies is a Scooby Doo Hoax.
Velma would explain that she didn't let the others in on the hoax because it was dangerous and she didn't want anybody to get hurt.
Monsters Unleashed, Legend of the Vampire and Monster of Mexico also all ended with a more conventional Scooby-Doo Hoax.
Halfway through, Curse of the Lake Monster looks like a Scooby-Doo Hoax, until the actual ghost of a witch takes Velma's body as a host and creates her minions of lake monsters. This is the second feature-length movie, animated or live, centering on Velma.
Big Eater: Shaggy, Scooby and occasionally Scrappy. If Fred wants to find the monster, Shaggy will volunteer to investigate the kitchen, and prepare a large snack for himself and Scooby — until the monster comes to interrupt the meal.
Big Friendly Dog: Scooby is a full-grown Great Dane and has never been vicious to anything, ever. Unless you count sandwiches.
In some of the early stuff, he gets to do some things that the latter episodes would never let him do, due to flanderization. There was the one where Scooby kept bouncing up toward an ape monster and ended up kicking it in the gut and such, just to save an actress. And then there's the infamous "John Wayne" impression in the episode "Hassle in the Castle". Let's not forget the time they were chased by a "haunted coat" (actually a goose under a coat) flying by itself, in which Scooby ended up snarling and making faces at it, to scare it away.
He still no problem getting riled up and volatile around cats, as well. Scooby has fallen into Took A Level In Jerk Ass territory in recent episodes of Mystery Inc., having had a falling out with Shaggy and nearly one with Velma. He redeems himself with a moment of awesome in "Camp Scare" and having since made up with Shaggy on Mystery Inc. and is trying to get Velma to like him again.
Big Shadow, Little Creature: An interesting variation occurs in "Mine Your Own Business," when the ghostly Miner '49ers runs for it when he sees and hears what appears to be a train approaching... only for it to really be Shaggy imitating a train horn and chugging, and Scooby going down the tracks with a flashlight and speaker Shaggy's train noises are coming out of.
Black Belt in Origami: In "Mystery Mask Mix-Up", Shaggy tries to bluff a Chinese ghost by saying, "I know judo, chop suey and Chinese checkers!"
Bootstrapped Theme: "The New Scooby Doo Movies'" theme didn't originally take off - in fact, the show directly after it didn't reference it at all. But then the "Scooby and Scrappy Doo Show" used it, and from that point on it was the running theme of the series for ten years.
Broad Strokes: The Shared Universe they exist in is notably very vague with The Original Series, Thirteen Ghosts and The New Adventures, taking place firmly within each other, the nineties movies taking place after their retirement from the former adventures, A Pup Named Scooby doo as a Spinoff Babies prequel and What's New Scooby Doo and its movies as taking place (ostensibly) with in the same universe. The Live Action Film series and Shaggy and Scooby Doo Get A Clue are in question however and both The Mystery Revealed and Mystery Incorporated take place in Ultimate Universes.
Brother Chuck: Fred and Velma inexplicably vanish in The 13 Ghosts of Scooby-Doo. Fred, Velma and Daphne were absent in the shows made from 1980 through 1982. And then Daphne vanished, too, leaving just Shaggy, Scrappy, and Scooby in the three syndicated TV movies.
Captain Colorbeard: Redbeard in "Go Away, Ghost Ship." He makes a second appearance in 1972's "The Ghostly Creep from the Deep," but in that story, he and his pirate crew are all ghost white and the voice is different (John Stephenson in "Ghost Ship," Lennie Weinrib in "Ghostly Creep").
One of the TV movies has a variant with a white stripe in his beard: Captain Skunkbeard.
Captain Obvious: Mystery Inc. will often point out things that are happening or just happened that should already be obvious to the viewer.
The Cast Showoff: The gang themselves, but most notably Velma in the movie Scooby-Doo and the Legend of the Vampire where they pose as contestants in the rock show contest (as The Meddling Kids) and eventually win by default. Velma sings the "Scooby-Doo, Where Are You!" theme. Poor child was petrified at first, but as she started singing, she put on quite a show.
All five members of the gang and some of the other characters sing throughout the 2012 made-for-video feature Scooby-Doo: Music of the Vampire.
Catch Phrase: Lampshaded in Scooby-Doo and the Samurai Sword, when the team finds out that the normal episode formula had turned into an Evil Plan, all of the characters say their catchphrases, ending with Fred:
Fred: "Um, uh...aw, darn it, I still don't have a catchphrase!"note He has said, "Creepers!" on occasion.
Chekhov's Gun: From The 13 Ghosts of Scooby-Doo, Flim-Flam was selling a concoction known as "Lots of Luck Joy Juice" when we first see him. One of the ingredients was Wolfsbane, and a splash of it was enough to cure the werewolf villagers that put the gang into a corner.
Cobweb of Disuse: In "What the Hex is Going On?", the old Kingston Mansion has these in the background (corners, connecting furniture to walls). Also present in the Vasquez Castle (notably on the portrait) in "Hassle in the Castle".
Coffin Contraband: In The Scooby-Doo Show episode "The Harum-Scarum Sanitarium" the villains were trying to smuggle gold in the coffins.
Comic Book Adaptation: Scooby has been in comic books since December 1969, published by Gold Key/Western Publishing, Charlton, Marvel, Harvey (reprints from Charlton), Archie Comics and the current publisher DC Comics. The first ten issues of the Gold Key run of Scooby Doo comics featured either truncated or very loose adaptations of TV episodes. Two episodes were made into comic stories twice: "A Clue For Scooby Doo" (Gold Key, DC) and "Spooky Space Kook" (Gold Key, Archie Comics). The first Marvel Comics issue featured a truncated adaptation of the 1976 episode "The Ghost Of The Bad Humor Man."
Zig-zagged: The pilot episode of Scooby & Scrappy-Doo ("The Scarab Lives!") was loosely based on the first story of Scooby-Doo Mystery Comics #24 (Gold Key/April 1974, "Mark Of The Blue Scarab").
Starting in October 2010, the DC comic began billing itself as Scooby Doo, Where Are You!, the first time the comic has been billed as such since October 1976.
Gold Key, known for taking continuity liberties, started making the gang ghost breakers for hire starting with issue #14. If this continuity is to be followed as any sort of canon, then issue #21 has the gang with the following Zodiac signs: Scooby—Aries, Fred—Pisces, Shaggy—Leo, Velma—Virgo, Daphne—Gemini. Charlton's stories are best left undiscussed.
Conspicuously Light Patch: When the spot on the floor that the gang is standing on suddenly turns a lighter color, you know that they're about to fall down a trapdoor.
When anything is colored differently than the other things in the scene (and isn't supposed to be), be it lighter or darker, someone will inevitably grab it or use it in some other way.
It may also follow that if doesn't have an ink (or xerox) line, it's the background. If it has the ink/xerox line, it's a waiting trapdoor.
The monster in the first movie is The Scrappy himself, wanting revenge for the team dumping him at the start of the movie. In the second film, most of the monsters are classic 'Doo bad guys, as is the real villain.
The Mysteries Incorporated series starts off with museum exhibits of several of the same villains the second film mentioned. Which can be somewhat confusing to people who watched the premiere, which was preceded by the second film.
Continuity Reboot: Scooby-Doo!: The Mystery Begins deletes everything A Pup Named set in the continuity other than it taking place in Coolsville.
Not necessarily, this was just the live-action version after all. More likely could be considered an Alternate Universe.
Conveyor Belt-O-Doom: A memorable one (That's Snow Ghost) had Velma tied to a log heading for a large circular saw.
Lampshaded by Shaggy in "Don't Fool With a Phantom" as he and Scooby are placed on one by the Wax Phantom:
Shaggy: "Not the old ride-on-the-conveyor-belt-into-the-wax routine. Oh, no. Like, that went out with the silent movies, Phantom, old pal."
Conviction by Contradiction: One What's New episode has the culprits turn out to be a man and woman pretending to be Sickeningly Sweethearts to secretly pass information to each other. After the unmasking, Velma says that the first thing that tipped her off was they were too lovey-dovey to be newlyweds as they claimed.
Crazy-Prepared: In What's New, Scooby-Doo?, Fred has made enough "special modifications" to the Mystery Machine to put Han Solo to shame, including modifying it to transform into a submarine and fitting it with a roof airbag which conveniently enables Shaggy to save Velma when she falls off a highrise movie set in "Lights, Camera, Mayhem". The submarine turned out to be a clue that The Game Never Stopped.
You could probably count the would-be Scooby Gang from The Venture Bros. as well. But that was more a parody.
The Addams Family, Batman and Robin (the Adam West version, later used on Superfriends), Don Knotts and the Globetrotters all actually appeared in the opening sequence for that season. Reruns often have people wondering who the heck Don Knotts is.
Don Knotts was in an episode parodying 'The Andy Griffith Show'' and an episode where he was a goofy Barney Fife like detective.
Crouching Moron, Hidden Badass: In one episode with a clown that hypnotizes people (Bedlam In The Big Top), Shaggy and Scooby remember what the clown did, so when he tries it on them again, they use mirrors to deflect the spell back at him, thus incapacitating him. That and when they pilot a bulldozer to tackle Steve in Alien Invaders. In addition, there's the mini-golf episode from "What's New, Scooby-Doo?" where Shaggy took the reins to try to solve the mystery for the majority of the episode. In that same episode (A Terrifying Round With A Menacing Metallic Clown), Velma goes off cowering with Scooby as her secret fear comes to the surface—she's frightened of clowns.
The comic book adaptation of "Bedlam In The Big Top" (Gold Key #9, Dec. 1971, retitled "The Phantom Clown") retroactively subverts this—Velma is the hero of the story as she hypnotizes the clown with his own gold coin.
Shaggy and Scooby-Doo are secretly ninjas. In situations where they can't be the whimpering cowards, they pull amazing feats. In Scooby-Doo in Where's My Mummy?, they leapt from falling platform to falling platform to keep from plummeting to their dooms. Scooby-Doo and the Samurai Sword also counts towards this.
Cute Monster Girl: In Ghoul School, Shaggy, Scooby and Scrappy become gym teachers for a bunch of them.
Cut Short: Scooby-Doo and his friends never did catch all 13 ghosts from The 13 Ghosts of Scooby-Doo. Technically, only 11 ghosts were shown being caught at all - and no ghosts were captured in the pilot.
This is debatable, as there was an episode or two where they could have conceivably caught others. The last episode did seem to be written with End of Series Awareness.
Darker and Edgier: Scooby-Doo on Zombie Island and Scooby-Doo and the Witch's Ghost are the darkest of the animated films. Cartoon Network made an awesome promo for Scooby-Doo On Zombie Island when they aired it on their animated movie spot. It only used the most thrilling scenes and was set to climactic Ominous Latin Chanting (possibly O Fortuna). Never before did Scooby-Doo seem so intense.
The new series, Scooby-Doo! Mystery Incorporated, although not much. It's definitely not cynical, but the universe as a whole is a little less idealistic, and the jokes, characters and events are more mature.
Dark Is Not Evil: The Hex Girls, a spooky-themed rock band that shows up occasionally in 90's-and-later versions (the direct-to-video movies, What's New, and Mystery Inc).
The Goblin King (Voiced by Tim Curry) may be the ruler of all things Halloween, but he's also a fair (though strict) ruler and he cares deeply for his fairy daughter.
This is the twist of Scooby Doo on Zombie Island the creepy rotting zombies aren't evil, they are trying to warn the visitors of the island so they won't end up like them.
Velma, of all people in the episode Scooby Doo Meets Dick Van Dyke as she, Fred and Dick see Daphne having fun on a bump-'em cart:
Velma: Hmph, Women. (realizes what she said) What am I saying?! I'm one of them!
Distressed Damsel: In the two shows with the Three Stooges, scripter Norman Maurer seemed to like getting Velma in a nice mess. In Ghastly Ghost Town, a mysterious figure sends her down into the mine shaft, while in The Ghost of the Red Baron, she is sent airborne in a bi-plane she doesn't know how to operate. Oh, andDanger-Prone Daphne.
Easily Forgiven: "What's New, Scooby-Doo?" occasionally had the culprit be let off the hook if they had arguably sympathetic reasons or if nobody got hurt, even if by their actions the monster would have very nearly killed someone. "Roller Ghoster Ride" is a good example of this, involving among other things Fred, Daphne and Velma almost getting diced up by a giant fan thanks to the monster's sabotage, along with tons of dangerous situations coming from sabotaging amusement park rides which would've ended up fatal if not for dumb luck or quick thinking, with no real consequences for the culprit.
Either/Or Title: Several episodes throughout had unused Either-Or Titles. Among them:
Scooby-Doo Meets the Addams Family (Wednesday Is Missing)
Sandy Duncan's Jekyll and Hyde (Scooby Doo Meets Sandy Duncan)
Scooby-Doo Meets Laurel & Hardy (The Ghost of Bigfoot)
The Caped Crusader Caper (The Sighing Flute...er, Flying Suit)
Scooby-Doo Meets Jeannie (Mystery in Persia)
Scooby-Doo Meets Dick Van Dyke (The Haunted Carnival)
Who Was That Cat Creature I Saw You With Last Night? (Make a Beeline Away from That Feline)
Also in "Hassle In The Castle": Velma sees and verbally acknowledges that the Shaggy head protruding from half of a magician's saw-in-two box was a dummy head. Shaggy pops up from the other half and says "Somebody mention me?"
Family-Unfriendly Death: The death of the cat people in Scooby Doo on Zombie Island goes straight into Nightmare Fuel. Also the death of the former inhabitants. Being forced to go into a sea where alligators (or crocodiles?) just wait for their meal? Charming.
The entire gang suffer one at the end of The Scooby Doo Project. The last we see of them is the monster coming towards them then the camera cutting out and the announcer telling us no trace of them was ever found.
Family-Unfriendly Violence: In Scooby-Doo on Zombie Island, there are a few examples of this. One zombie has his head ripped off and two get cut in half.
Shaggy: The Lancer: When the gang does split up, Shaggy leads one half. Shaggy (along with Scooby) often notices creepy things that Fred had missed. Shaggy is likes to sneak away with Scooby to eat a large snack.
Daphne's klutziness is turned up to eleven in Abracadabra-Doo.
Mystery Incorporated Fred becomes completely obsessed with making traps.
Scooby's cowardliness, during the first season.
When it comes to courage, both Scooby and Shaggy have been incredibly flanderized since the original series. The duo was always reluctant to go ghost-chasing (Daphne was also less enthusiastic about their adventures) but more recent incarnations makes this viewer wonder how the two function at all with the group.
Velma is normally a bright girl, but she becomes a bit inept (not of her own doing) when she loses her glasses. However, a particular bit of brain fart is puzzling. In "The Ghost Of The Red Baron," she is sent airborne in a bi-plane she has no control of, and she forgets the international distress radio call (followed by an atypical Daphne response):
Velma: Let's see, what was it? January? February?...March? April? Mayday!! That's it!!
Daphne: That's Velma. What's she calling "mayday" for? Today's June 5th!
In What's New, Scooby Doo?, Velma became a bit more as snarky as she was smart, albeit her fear of clowns came suddenly to the surface. And in Scooby-Doo! Mystery Incorporated, she tacks on cynicism, her obsessiveness to Shaggy and her contempt (as of episode 10) of Scooby.
Food as Bribe: Shaggy and Scooby can be coaxed into doing anything for food, namely Scooby Snacks.
Foreshadowing: Zombie Island has several signs linking to the end of the mystery, including one in one of the chase sequences, where a Zombie gives Shaggy a vine to pull Scooby out, at first, it looks like just a gag involving the whole "Monster helps them to save themselves", but it foreshadows that the Zombies are not as evil as they're made out to be.
Fortune Teller: In the Where Are You episode "A Gaggle of Galloping Ghosts", the gang meets a Gypsy fortune teller who gives them dire warnings. She turns out to be the episode's villain in disguise.
Frank Welker: Fred is his first role and one of his best known roles, and Frank still voices the character today many years since he had started. With the passing of Don Messick, Welker voices Scooby, too.
Free-Range Children: The gang probably isn't that old, yet they run all about creation solving mysteries. This wasn't changed at all in A Pup Named Scooby-Doo. Well, in Pup they mostly stayed in one town, at least.
Functional Magic / Where They Were: The conclusion of Scooby Doo and the Goblin King. The Goblin King permits Shaggy and Scooby (the main heroes) to retain their memories of the events that transpired but he erases the memory of Fred, Velma and Daphne. Shag and Scoob pull up in the van as their buddies' heads clear, not knowing what happened last:
Daphne: Shaggy! Scooby!
Velma: Where were you two all night?
Shaggy: (He and Scooby exchange knowing glances) Like, you wouldn't believe it if we told you!
G-Rated Drug: Scooby Snacks. Either that, or they're just a very convenient, cheap, salted-chip style appetizers whose demand is fueled by an unspoken drug, ie, marijuana.
Played with in the parody show Harvey Birdman. In the episode "Shaggy Busted." The Mystery Machine is seen smoking up (from an overheated engine, based on the original episode), and we hear Shaggy exclaim "Scooby... doobie!"
Gadgeteer Genius: Velma arguably qualifies, at least in What's New, Scooby-Doo?. where she's capable of building (among other things) a robot dog with a remarkable number of functions and an MP3 player the size of a sugar cube (though the latter lacked earphones). In the same series Fred also at least comes close with his improbably sophisticated modifications to the Mystery Machine.
Genre Blindness: Particularly in the original series. No, the gang will never figure out or even guess that the monster is just a guy in a costume right away, no matter that the last few dozen monsters were all guys in costumes. They have to wait until the end of the episode.
Debatable. Their scared reactions might just be because despite someone being an obvious Scooby-Doo Hoax, he's still a crook and might want to harm them for getting in his way, and a number of times Fred and Velma express a degree of skepticism on principle.
Genre Savvy: In the first episode of What's New, Scooby-Doo?, the second they notice the monster, Fred assumes from the start that it's just a costume with a guy inside. Unfortunately, Shaggy shows him that the monster's body is transparent and the Fred's genre blindness returns.
They latch on to this trope much more firmly in the movies (particularly the live-action ones). Unfortunately, that's about when the monsters actually do start turning out to be demons and zombies and whatnot.
In one episode of What's New, Scooby-Doo?, Shaggy and Scooby have the foresight to bring along their own box of Scooby-Snacks. Pity they forgot the milk, though.
In Mysteries Incorporated, their town has a museum of monsters (all of whom, according to Velma, were guys in masks).
Genre Shift: Zombie Island transitioned from a straight Scooby-Doo story, to a supernatural horror mystery film.
In A Scooby-Doo Halloween, Velma's cousin says "I'm 18, able to legally..." [looks at Fred] "...vote."
Arguably every drug reference in the show. Use of the word "munchies" is not uncommon.
In Curse of the Lake Monster, Daphne's Uncle says "Well, it looks like I'll have to go back to my old life as a international playboy." Then again, that may have been an element that garnered the movie a TV-PG rating.
In Scooby-Doo on Zombie Island Shaggy and Scooby get jobs as customs officers. They were apparently supposed to be searching for contraband foods, and were subsequently fired for eating the contraband.
Daphne walks in on Velma floating in midair:
Daphne: Wow, a real case of levitation! (Velma floats even higher) This just gets better and better! Velma:(pulling her shirt to her thighs) Maybe from where you're standing!
"Blue Falcon" is United States military slang for "buddy fucker" (somebody who pursues his own interests at the expense of those who he's supposed to look out for).
Growing Muscles Sequence: one in each of the first two live action movies. The first happens to a villain and could be viewed as Nightmare Fuel, while the second happens to Shaggy and is played for laughs.
Hair Decorations: Velma has a flower in her hair at the end of "A Tiki Scare Is No Fair" as she does the hula in her Hawaiian grass skirt. For all her bookworm "plain Jane" descriptions, she was really quite adorable.
Hartman Hips: All over the place in Abracadabra-Doo. Made a bit more obvious due to the movie having lots of Male Gaze moments, and including three of the girls showing up in skintight outfits at least once.
From The 13 Ghosts of Scooby-Doo episode "It's a Wonderful Scoob," a mishap with Time Slime's scepter shows him all the horrors he's faced in his life, Scooby becomes so traumatized that he goes into a 10-Minute Retirement. Vincent shows him a Bad Future to help snap him out of it, though.
Hollywood Torches: Shaggy finds and uses one in Where Are You episode "Spooky Space Kook".
"Home Alone" Antics: A regular occurance after a Let's Split Up, Gang when Scooby & Shaggy are on the run from the monster of the week, then set up some kind of elaborate scenario in order to confuse the monster.
In A Scooby Doo Valentine (episode of What's New, Scooby Doo?) the imposters of the gang are unmasked and revealed to be caricatures of their voice actors (Frank Welker, Casey Kasem, Grey DeLisle, Mindy Cohn). In fact, the valentine they find as a clue has the gang's names written in the handwriting of the voice talents.
Ronald Reagan, U.S. president from 1981 to 1989, appears in caricature (voice of Fred Travalena) in the 13 Ghosts episode "It's A Wonderful Scoob."
Shaggy and Scooby always seem to end up finding the weekly monster despite their cowardice, laziness, and complete lack of investigative skills.
Despite the inevitable failure of Fred's convoluted traps to catch the monster, the monster usually ends up trapped by the end of the episode anyway.
Is It Always Like This?: The Scooby-Doo comic book has an issue where a character asks, "And this happens everywhere you go?" Shaggy responds with, "Well, there was this one time where Fred took us to a flower shop..."
Jumped the Shark: invoked Taken literally in the What's New episode "Lights, Camera, Mayhem" as Scooby and Shaggy sail over a tank of sharks on a motorcycle, with Velma cracking the obvious punch line:
Velma: Who would ever think that Scooby would jump the shark?
Kavorka Man: It's not so much that Shaggy is a pimp, but many episodes and movies have shown that many an attractive female seems to think Shaggy is hot. Most recent example is the made-for-video movie Scooby Doo! Abracadabra Doo, which has Velma's kid sister Madelyn with the hots for Shaggy. And now, with Scooby-Doo! Mystery Incorporated., Velma does as well. One wonders how the next family get-together might go. ("I guess we Dinkley sisters have something in common after all.")
Kissing Cousins: One episode of The Scooby-Doo Show featured Scooby-Doo and Scooby-Dum's cousin Scooby-Dee. Both Doo and Dum found her very attractive. Whether or not the fact that they're all dogs eases the weirdness is up to you.
Lampshade Hanging: What's New occasionally mixed up the standard formula, while also making fun of it, including a few situations where the culprit turns out to be no one the gang (or the audience) had met before.
Occasionally? It revels in hanging lampshades on the tropes of the old cartoon, especially in the movies. Common targets include The Reveal dialogue, quirks of the characters, plot tropes, and potential fakeness of the monster. Mystery Inc. looks to be headed in the same direction; for instance, it's changing "You Meddling Kids" into a Mad Libs Catch Phrase.
And we won't even start on A Pup Named Scooby-Doo.
Let's Get Dangerous: Shaggy and Scooby when anyone they really care about is in trouble. There was even one moment when Velma was captured and Scooby turned down a Scooby Snack saying he didn't need it to be persuaded to help rescue her.
Let's Split Up, Gang: Trope Namer, ahoy! It's notable that in the more modern adaptations, it's nearly irresistible to play with this trope more than a little.
Limited Animation: Scooby-Doo was infamous for it. Oddly enough, it doesn't apply to the first few DTV movies (Zombie Island, Witch's Ghost, Alien Invaders, Cyber Chase) since the animation is quite lively and fluid. Nowadays it's back to looking pretty cheap. But a lot better than before.
Lampshaded in the 13 Ghosts episode "That's Monstertainment." Scooby appears in a mock-up of the MGM opening title sequence where it reads "Ranna-Rarrera" below it and "Limitus Animatus" around Scooby's face.
Long Runner: Still making new episodes/movies, 40+ years later. In those years of the franchise, there have been 451 series episodes (these include eleven-minute and seven-minute installments and Scooby and Shaggy's Laff-A-Lympics appearances), 10 guest appearances on other shows, two parody spots, 8 specials, 5 made-for-TV movies, two theatrical movies, three commercial shills (2005 spot for Dove shampoo with Velma, Wilma Flintstone and Jane Jetson; 2006 spot for DirecTV with the whole gang, a 2014 spot for State Farm with the gang), a movie theater spot (the gang busts Daffy Duck for jabbering on a cell phone in a theater), and (so far) 21 direct-to-DVD movies. A new series, Be Cool, Scooby-Doo! starts later this year.
Magic Skirt: Velma in the first live action movie (where she's dangling upside down by one foot◊—word is that Linda Cardellini had her skirt taped to her legs), and Velma and Daphne in the What's New episode "Ready To Scare" (the entire gang suspended by their feet).
In "Haunted House Hang-Up," Velma, Shaggy and Scooby fall into a well feet first. Velma's pleated skirt does not rise.
Subverted in "Recipe for Disaster," where Velma and Daphne hold their skirts down after a high-power floor dryer (used after the gang gets soaked) is activated.
Scientists and technicians tend to have names either related to their field of study, or to science in general (e.g. Professor Angstrom). Other minor characters' names sometimes reference their line of work too (e.g. Sue Crose, maker of a sugary drink).
Mustache Vandalism: Scooby and Shaggy have done this many times, usually with the "painting/statue coming to life" variation.
My God, What Have We Done?: Velma's uncle Evan and aunt Meg, when their daughter Marcy turned out to be the Villain of the Week in A Scooby-Doo Halloween. They felt guilty for putting Halloween before their own daughter's birthday.
My Eyes Are Leaking: Velma towards the end of Music Of The Vampire. The witch's hypnotic gas is making her eyes water, and Daphne (who is dazed and tied to a swamp altar) thinks Velma is crying.
Mythology Gag: The end of The Mystery Begins features live reenactments of parts of several Scooby-Doo opening themes, including Scooby Doo, Where Are You!, The New Scooby Doo Movies, and What's New, Scooby Doo?.
The entire movie is one big Mythology Gag, when you come to think of it.
A flashback to Velma's childhood in What's New, Scooby Doo? uses the art style of A Pup Named Scooby-Doo. It depicts why she's afraid of clowns.
In addition, one of the episodes features Fred and Velma indisposed, leaving only Daphne, Shaggy and Scooby to solve the mystery by themselves, a la all the later shows before A Pup Named Scooby-Doo.
In the first episode of Mystery Inc., Shaggy mentions that he fell asleep watching "a Vincent van Ghoul movie". Vincent van Ghoul was the group's mentor in The Thirteen Ghosts of Scooby Doo.
In the same episode, several previous mysteries are seen in a museum, with Velma mentioning a few mysteries, and giving out the motives and identities of the "monsters".
In A Scooby Doo Halloween, Shaggy is dressed as a werewolf like in Scooby-Doo and the Reluctant Werewolf.
In "Curse of the Lake Monster", the gang receives a check for $10,000 from The Bank of Hanna-Barbera.
Also in that movie, Fred and Daphne pretend to be manniquens, dressed in their classic clothing from the cartoons. Fred sees his reflection and contemplate this before saying "nah".
In Scooby Doo and the Cyberchase, the gang's simulated duplicates inside the video game are drawn in the style of the older series. Lampshaded with a quip that the game's designer hadn't seen the gang in a while when he programmed it.
The Scooby segment of the April 1st Batman: The Brave And The Bold episode is not only designed and animated in the same way as the Scooby Doo Movies episodes with Batman and Robin, but it also has the same animation glitches—Batman's neck is exposed (which Bat-Mite points out to his digust) and another scene shows Batman with a gloveless hand with a ring on his finger.
In the episode Scooby Doo And A Mummy, Too, Velma is disguised as Cleopatra (to Shaggy's Marc Antony) in an attempt to hide from the mummy. She actually dresses up as Cleopatra in Scooby Doo In Where's My Mummy? as part of the Scooby-Doo Hoax she helps stage.
In "Guess Who's Knott Coming To Dinner," Don Knotts (in the guise of Captain Moody's first mate) identifies Fred as Captain Moody's nephew Ronald. This is probably a nod to Ronnie, which was Fred's original name until he was renamed after CBS programming head Fred Silverman.
The 2012 special Spooky Games uses the same premise as the 1973 Scooby Doo Movies episode "The Spirited Spooked Sports Show'' (with Tim Conway)—Shaggy becoming a competitive runner who runs fastest when he's scared.