[AC spoilers] In "The Atlantis Complex", Artemis claims that his alter ego is Orion because in the Greek myth, Orion was Artemis' mortal enemy and she summoned a scorpion to kill him. That's completely wrong. One version says that he hunted alongside Artemis until he got bloodthirsty and vowed to hunt every animal on Earth... Think about that for a second, Orion fought alongside Artemis - And what is Orion hunting? Holly's heart. Why would Artemis not want Holly to know that they are fighting along side each other? Well, considering that it's Artemis... Of course, it could still just be a lack of research, but....
A lot of versions also say that Eoin Colfer was actually correct about this. The myths vary.
In many time travel stories, when a person is threatened to be erased from existence because interference in the past sets off a chain reaction of events that causes their present selves to not exist, they usually just fade out of existence and reality simply changes along with their vanishing, with complete disregard for the fact energy cannot be created nor destroyed. Eoin Colfer ingeniously demonstrated an obedience to the Law of Conservation of Energy by showing what most likely would happen if you killed your past self while they were in the present a la Grandfather Paradox. You "cease to exist" alright, but reality does not change around you, and "ceasing to exist" equals blowing up like a nuclear bomb.
In "The Time Paradox", Holly tartly informs Artemis that his elf-kissing days are over. As a matter of fact, Artemis has one elf-kiss left in him - and it saves his life in "The Last Guardian".
Arty, you closet sap. Giving the lady a toenail clipping would have been far more reliable and efficient. Anyway, what if she'd washed her face?
If all else fails, she still has a gold mine of his DNA embedded in her face. Remember how they swapped eyes?
In The Lost Colony, Abbot forces the demons to maintain a highly militaristic culture, and makes specific effort to educate young demons to become Blood Knights. What triggers the warp phase? Bloodlust. Also? "When an imp warps, that's the end of any magic they may have had." What does Abbot fear the most? What is the only challenge to his authority on the council? A warlock. He's deliberately arresting the only threat to his rule. Unlucky for him, No.1 turned out an Actual Pacifist.
A page-long dialogue sequence between Holly and Artemis midway through the second book where Holly asks why Artemis is so cold-hearted when his father was more noble. His answer was that he "made a mistake." Said mistake is explored in-depth in the sixth book.
Also not lost on the fandom: That part of the Last Guardian where Eoin Colfer says Trolls are smart, which actually makes sense. Lets take the Chimpanzee, considered to be the smartest non-human animal. But what most people don't know is that Chimpanzees are EXTREMELY violent and aggressive-in that one of the first thing they do when they fight is literally RIP THE GENITALS OFF. Not to mention they actually are willing to KILL a chimp baby in order to have sex with a female. Trolls given their primate-like description are probably similar to chimpanzee in behavior, they can be intelligent, it's just that they prefer to fight and are hyper-violent.
Well, there are a lot less fairies, so most of the pollution probably is still humans, by virtue of our sheer numbers. There are numerous hints throughout the series that it's a lot less black and white than the fairies seem to think.
The book also establishes that the gas-powered wingset Holly is using is an incredibly obsolete model that is only still on the LEP inventory because budget issues prevented them from replacing it with more modern electric-drive versions.
In the first book, in order to escape the effects of the bio bomb, Artemis, Butler, and Juliet mix sleeping pills with champagne, an alcoholic beverage. Wasn't that basically how the the late Heath Ledger bought the farm, that is, by mixing sleeping pills with alcohol?
Already addressed in the Headscratcher page, odds are Artemis didn't actually mix sleeping pills with Champagne, but was probably some extremely powerful sedative(as sleeping pills don't provide instant knock out). He was just talking about celebrating with Champagne because he knows that if he told Butlers that it was a sedative he would subconsciously fight it off and considering they had literally seconds before the bio-bomb is launch he couldn't risk that.
Artemis never takes out his iris cam while showering in EC. This either (1)Fuels the fire for the Holly-Artemis ship as it says she's watching through the iris cam, or (2)Ho Yay between Foaly and Artemis, which has been mentioned by certain people (or, y'know, they could've just turned away from the screen for half an hour, but that's not as fun to imagine).
If you're an animal lover, a good part of "The Last Guardian" counts - what happened to all those animals possessed by the berserkers after they departed? What about the dog the troll kicked, or the one Holly shot?