Calling Card: The Chickerufus always paints an eye on the tent he visits, then comes back the next night for his dinner.
Canis Major: Anasazi's true form is a giant, talking, animated Buffalo painting of a coyote.
Can't Hold His Salt: Trench from Blood Diamonds. In Swimming in Red, he mistakes Rumble Saddlon for a mare, addressing him as Daisy, and when told that's not his name goes on to call him various other mares' names, culminating in Celestia). Then he flirts with a barstool...
Chekhooves' Gun: Every major artifact Daring has recovered in her adventures returns in the last (in-verse chronologically wise) book as a part of Ahuizotl's master plan. Since this book wasn't the last one published it has the rare honor of having the pay off to "guns" that haven't shown up yet, as well as a few artifacts we still haven't seen outside of it. Some of the artifact descriptions are deliberately vague to allow for later books.
Chronic Backstabbing Disorder: Besides his main betrayal, Shifty Gaze at various points robs Daring's cooler of everything in it, abandons her early into the temple after she's caught in a trap, and lies about an expedition with a different pony to make it sound like he did all of the work. All in the first third of the book!
Chunky Updraft: The Steelclad Sorceror tends to cause this when particularly angry. Which is very, very often.
City of Adventure: Subverted, so far at least, with the city of Arkhoof. Daring has only visited a few times, usually to study a book at Agaether University, but strange narrative events constantly happen there. The city as a whole is described in abnormal, vivid detail. There are odd Meaningful Background Events that never actually come to anything. A number of locations are brought up, repeatedly sometimes, that Daring never actually visits. Weird things are happening in town but Daring doesn't have the time to investigate. It seems like Arkhoof was being set up to be significant, the setting of a whole book perhaps, but it never came about.
Cold-Blooded Torture: In Tinker's Seal, after making it back from the Blank Village, Mareton manages to capture Storm Talon and in an attempt to find out about the progress of the others, he breaks his wings. When he's only answered with swears, insults, and the occasional thanks for offing professor Nagridge, threatens to cut out his tongue and shove a parasprite down it. Ghoul manages to sniff Mareton out, but he manages to escape unscathed.
Comic Book Adaptation: There have been a few. The most recent series almost reached 46 issues before the publisher went bankrupt. The best known series was illustrated by the famous artist Crow Quill Nib roughly seventy-five years ago. Occasionally, collected reprint graphic novels are released by various publishers.
An artist from Fillydelphia has recently started talks with Polo House to start an Ultimate Universe series.
Arguably the most infamous of all the comic adaptations is the limited Mareval print run, which only lasted for ten issues before bad publicity and low sales killed it. They were later collected into graphic novel format and redistributed, oddly enough leading to the formation of a cult following of the comics in question.
Comic Book Time: Particularly blatant in Trials of Unity, where the technology is leagues beyond what was capable back when Griffon's Goblin was published decades ago. All the recurring characters otherwise remain frozen in time, although Calypso at least Lampshades this hilariously to the confusion of everypony.
This gets worse for Tinker's Seal, which requires previous knowledge of pretty much the entire expanded universe, barring both the Star Quest and Blood Diamonds series.
Convection Schmonvection: Daring Do's escape from a room filling with lava, at one point with her standing inches above it (bare-hooved, even), without harm. She even gets a face-full of steam with no ill effects.
Cool Airship: The Explorer, loaned by the university, which carries Daring and Bravado around the globe in Staff of Star Swirl.
In the first Blood Diamonds book, main villain Colonel Talonus has an enormous armored war zeppelin called The Iron Fist.
Coco Pie's airship,The Sweet Dream.
Storm Talon's last command, The Storm's Vengeance, a Tiger-Hawk class aerial dreadnought, makes a brief appearance in Griffon's Goblet and was one of the ships brought to bear against Inferno in Shrine of the Silver Monkey.
In The Skull of Ages, Marshal Goldstar has an enormous zeppelin called The Executor. Anne Bonfire later kills him and takes it for herself.
Cool Gate: The Assembler's modus operandi: With the information provided by its infiltrated constructs, it pinpoints the location of another suitable target, and turns a door or window nearby into a portal, which it uses to flood the area with anesthetic gas and start cutting.
Cool Pet: Grouchy the T-rex, while not exactly a pet per se, is considered one by Daring and company.
Corpsing: Nagridge has a few instances in the film of Temple of Nightmare Moon.
The Gag Reel of Staff of Star Swirl the Bearded has several outtakes of Shia LaBuck as Herpy corpsing at Lightning's funeral.
The Corruption: The Wooden Mask. It does some...interesting things to Daring. Rest in peace, Tennis Set.
The Blood Diamonds in the series of the same name give their bearers homicidal urges, the extent of which varies depending on the bearer in question, as well as which and how many of the Diamonds they possess.
This is basically Krastos' MO-just being around him causes it, although the stronger the pony's will is, the less effect it has. Those who let it fester in them too long eventually have their consciousness subsumed by his, turning into a copy of him.
Covers Always Lie: The scene depicted on the cover of Sapphire Stone never actually happens in the book.
Though it does appear in Zapapple Tock and the Sapphire Statue, as a Development Gag.
Creator Breakdown: In-universe, with Star Shimmer's paintings becoming terrifying after Earth Song disappears.
Creator Provincialism: the Brumbiland setting of Ember Roundup's Curse of the Golden Key, as well as its heavy focus on Outback Jack's family. Though it seems to be an isolated example, as her previous book was set in Saddle Arabia and she had little-to-no involvement with the Outback Jack sideplot in Tinker's Seal.
Crossover: Not in the main book series, but there was a memorable episode of the popular Trottingham radio series Professor Whoof where the good Professor and his companion met Daring Do on one of her adventures. No, really.
Roseluck: What? You're real?? I thought you were just a character in a book!
Daring Do: Real as the sun, Missy. Speaking of books, I did lose my journal a while back...
Daring also played a major part in a recent issue of the Mysterious Mare-Do-Well comic book series, accompanying MDW on a museum heist mystery.
Curb-Stomp Battle: Ahuizotl vs anyone when he gets serious. Except Rex. Rex is probably the only character Ahuizotl couldn't crush in a straight-up fight when he wasn't holding back. Which is why Ahuizotl later resorted to more underhanded methods.
Blackmane is also something of a subversion. Ahuizotl curb-stomps him SEVERAL times over the last third of the book, but Blackmane keeps getting back up due to being dead already.
Ahuizotl was on the receiving end of one from The Pikmin of all creatures. They were enraged that he would mess up their home, The Gardener's Garden. They literally swarmed all over him, not a pleasant thing. Counts as a Did You Just Buck Out Discord? since a single one is the about the size of a grain of rice.
The two golem siblings vs. anypony. Of course, them being war machines crafted by the Mad Tinker himself, this isn't that surprising.
Darker and Edgier: Daring Do and the Temple of Nightmare Moon (not to be confused with the more recent book Legacy of Nightmare Moon) is considered one of the darkest entries in the Core Sixteen series and one of the only movie adaptions likely to receive a 'PG-13' rating. See Once per Episode for just one example of the more somber tone.
Blood Diamonds starts extremely grim for a Daring Do series, and gets worse from there.
The Expanded Universe book Daring Do and the Coronet of Chaos, as it introduced Krastos, possibly one of the most evil characters in Equestrian history.
Breathing Weapons, featuring an antagonist who kidnaps griffon children and turns them into weapons, and the deaths of no less than five characters over the course of the story.
Platinius could give her a run for her money in this department. The bit with the mallet comes to mind.
Mareton utilizes these as well.
Dashing Horsepanic: Bravado, and how! For example, he fought off nine of Ahuizotl's Mooks using nothing more than his knowledge of the Veneightian backstreets, a vegetarian stroganoff, and his mandolin.
As does The Wooden Mask, where, after three chapters of Daring being manipulated and subtly controlled by the mask, "Disappearance" and most of the rest of the book focuses on Herpy's attempts to find Daring.
Staff of Star Swirl is one for Bravado, with him actually serving as the main character for the first fifth or so of the book before the real Daring Do shows up.
The Curse of the Golden Key gives some focus to Outback Jack in the first three chapters, who is investigating odd going-ons around a village, such as new wildlife, which, as it turns out, is actually old wildlife but in newer, more metallic forms.
Swinn and Dell get to actually help out with the mane plot in Cove of Candles.
Deadpan Snarker: All of the Do's have shades of this, although Daring herself displays it the most.
Even her pet macaw Calypso has shades of this.
Though Mirror Dreams can out-snark Daring when she wants to.
In a recent radio adaptation of Ruby of the Blank Village, Starlet is among those responsible for murdering Ruby after she gets her cutie mark, and takes such sadistic pleasure in it that she immediately ends up with a cutie mark of a bloodstaiend knife. This instantly gets her killed by Greyhoof, and the irony is lampshaded by Roneo, who then gets a cutie mark for irony appreciation, and is likewise killed.
The same joke appears in the book, but is a lot subtler - the marks are described, and the basic order of events is given, but the reader is left to fill in the implications.
The following characters have actually died and have come back, either true resurrection or as some form of undead in either the main series or the EU (alternate reality versions of them dying don't count): Ahuizotl (twice, once in the main series and once in the EU, both unexplained), Commandant Rex (comes back as a revenant), Attic Fan and the other imprisoned surviving members of the Colt of Smooze (turned into soulless by the Assembler), Gas Whole, Charity, Applesack (ghosts summoned by the Wandering Whistle), Princess Sparkler (ghost, unspecified manner of return), Sweetie Bottle (rebuilt as a golem by Princess Sparkler), King Hammerhoof (returns as a Nightmare), the entire Blank Village and the victims of Sunnytown (due to the curse, they return as Nightmares or Bone Fiends, or in Ruby's case, a ghost), Inferno (stated to be a zombie under Ahuizotl's control in Trial)
Defictionalization: Several of the items Daring searched for in the series were made into actual objects and most were sold at a Canterlot auction last year, half of which were bought by THE esteemed publishing tycoon pony J. P. Quillhorn.
Inverted with the Staff of Star Swirl the Bearded; the genuine article has been on display in the Canterlot Museum for the last couple centuries, and has been on several traveling tours in the last few decades.
Despair Event Horizon: Daring spends the start of the fifth book of Blood Diamonds here, attempting to get over the trauma of almost committing cold-blooded murder at the end of the previous book.
Dei Ex Machina In Shrine of the Silver Monkey, ape gods Margarita and Balthasarnote Megan and Danny come to Daring's rescue.
The mysterious Laurentia of the Red Mane gets Daring and co. out of a tight corner involving Diamond Dogs with augmented magical abilities in Temple of Nightmare Moon.
The equally mysterious Banizacherla deals with the Raptorians in Spear of the Windigos.
Did You Just Buck Out Discord?: In Amber of The Smooze, Desert Rose used the Eyes of Fatima on the Smooze as it was trying to submerge her while she was trapped in the Colt Leader's body. It cowed the Smooze into returning Desert Rose to her own body.
Do Not Do This Cool Thing: Nearly every time a new book comes out, some silly Pegasi decide to try the aerial maneuvers Daring Do does. It rarely ends well...
Which is why the author included the following exchange in the Young Daring Do novel Valley of Grouchy, after the first encounter with a dino.
Blinkamena: Can you teach me to do that somersault over the head. Zapapple: That was sheer luck, nothing more. You'll probably get yourself killed if you try it. I'd probably get myself killed if I actually tried to do it.
Door Stopper: Daring Do and the Ring of the Marengeti, sweet Celestia.
Alicorn's Shadow could give it a run for its bits.
Both topped by Tinker's Seal. The thing could easily be split up in at least five volumes, and each could easily pass for a normal book.
Do Wrong, Right: In Temple of Nightmare Moon, Professor Storm Talon catches Herpy trying to steal an airship to gather Daring's allies for a rescue, expresses disappointment in him... then shows him how to bypass the security measures.
Drama-Preserving Handicap: In Sapphire Stone, Daring's wing is injured upon making it to the island where the eponymous stone is found, and she's unable to fly for a few days. Conveniently, none of the temple's traps require her to fly, though it would have made it easier. Later books have more traps that have fliers in mind, so the author doesn't have to resort to this as often.
Zapapple Tock and the Sapphire Statue does something similar, with Zap being temporarily blinded in one eye.
Daring spends much of Cloud-Held Eternity as a filly, rendering her unable to fly, which makes navigating an Ancient Pegasus ruin that much harder. The loss of her cutie mark also dulls her instincts concerning traps and makes it somewhat harder to call on her knowledge and experience.
The Dreaded: Anypony who has ever heard of the Assembler is completely terrified when it starts to show signs it's back.
Drunk on Milk: Diamond Dogs find chocolate delicious. And inebriating. And toxic. Ghoul is known to snort cocoa powder and shoot chocolate sauce into his veins.
Dungeon Bypass: In Daring Do and the Wooden Mask, Daring manages to bypass most of the traps in the temple by forcing her way through a locked door in what was supposed to be a dead end.
Claddie's dungeon crawling method can be summed up as "make an educated guess as to where's the exit and tear down the walls between you and it".
Durable Deathtrap: This is normally played completely straight, but subverted in Wooden Mask, where the lock mechanism on one of the doors failed, leading to a surprisingly easy path through the temple.