Tropes A to B (Adaptation-Induced Plot Hole, Arc Villain, Berserk Button, Beware the Silly Ones, Big Brother Instinct, Bowdlerise, Break the Cutie) | Tropes C to D (Call-Back, Chekhov's Gun, Cliffhanger, Combat Pragmatist, Crouching Moron, Hidden Badass, Curb-Stomp Battle, Dark and Troubled Past, Deconstructed Character Archetype) | Tropes E to F (Early Installment Weirdness, Famous Last Words, Foreshadowing) | Tropes G to J (Heart is an Awesome Power, Hypocrite) | Tropes K to M (Laser-Guided Karma, Logical Weakness, Mass "Oh, Crap!", Moral Myopia, Muscles Are Meaningless) | Tropes N to P (Nice Job Fixing It, Villain, Oh, Crap!, O.O.C. Is Serious Business) | Tropes Q to S (The Reveal, Shout-Out, Spanner in the Works, Superpower Lottery) | Tropes T to Z (Wham Episode, Wham Line)
Being a Long Runner, it's inevitable that, looking back, elements from the series' beginning feel weird in retrospect.
- The two prototype versions of "Romance Dawn" are markedly different from the final version of One Piece. For one thing, adventurous pirates are called Peace Mains, and raping-and-pillaging pirates are called Morganeers. There's also a conspicuous lack of Calling Your Attacks, and Luffy was apparently much smarter than the final version.
- Kuina dying by falling down some stairs in Zoro’s backstory doesn’t mesh well at all with later One Piece. While it’s a shockingly sudden and very realistic way for someone to die, One Piece characters- up to and including children- eventually came to be well known for being Made of Iron as the series went on. So, for someone who was stronger than the already-abnormally-strong kid Zoro to just fall down some stairs and die… it would seem ridiculous happening to any character today, even if they were just a child.
- Given the manga was only supposed to run for 5 years before Oda expanded the story, this was bound to happen. In the beginning, the Grand Line was a crazy, mysterious ocean barely anyone could survive. Later, it's established not only that plenty of perfectly normal people are native to the Grand Line, but pretty much any pirate worth his salt can navigate it.note Then, it turns out there's a previously unheard of second half to the Grand Line known as the New World, while the "crazy mysterious" first half is now known as Paradise.
- Laugh Tale was originally called Raftel in English before its meaning was revealed, and it was implied to simply be at the end of the Grand Line with only Gol D. Roger-level pirates able to reach it. Post time-skip, it's revealed that reaching Laugh Tale isn't just following the Grand Line to the end but is somehow impossible to find without the Road Poneglyphs to create a map. That said, Lodestar Island (the second to last island) still has Laugh Tale's original description.
- Zoro's terrible sense of direction wasn't present for the first few arcs. This becomes noticeable in the Kuro Arc, where he and Luffy are late to the confrontation with the Black Cat Pirates. While Luffy, who also has a bad sense of direction is late due to getting lost, Zoro's excuse is just that he got stuck in an oil patch. After getting un-stuck, he has no issues finding his way to the scene.
- At the beginning of the series, the very existence of Devil Fruits was heavily questioned in the setting, with many not even having heard of them at all. As the story progressed, it has been shown that there are many prominent people with Devil Fruit powers, such as high-ranking members of the government and many of the most powerful and well-known pirates. Additionally, information spreads easily in the One Piece world, what with the existence of cameras and video phones. As the series has progressed, it's become incredibly unlikely that anyone in the One Piece world doubts the existence of Devil Fruit.
- Alvida was the first person to make the claim that Devil Fruits were a myth. However, she managed to find and consume a Devil Fruit in no more than A WEEK after meeting Luffy, and she didn't even need to go to the Grand Line to do it. Which means somewhere between getting punched into the sky, and meeting up with Buggy, she just HAPPENED to stumble across a "super rare" Devil Fruit.
- How Buggy got his Devil Fruit powers. The pirate crew he was in as a boy doubted the existence of Devil Fruits, and he was even able to get away with stealing one by eating a fake and pretending it didn't do anything. Except that this crew was later revealed to be Gol D. Roger's crew, a crew that should have been encountering Devil Fruit users left and right, especially considering the fact that they'd sailed the entire Grand Line.
- When Luffy carelessly pokes open the holes in his Straw Hat that Nami just sewed shut after his fight with Buggy, she punishes him by poking his face with her needle, explaining that hitting him wouldn't actually work. Later in the story, she'll dish out plenty of slapstick on Luffy despite his supposed immunity to blunt force like fists (at least without Color of Armament Haki).note
- When Sanji first met Luffy, he was naive about Devil Fruits and their side effects; Zeff even had to tell him that Devil Fruit users can’t swim, and thus Sanji had to rescue Luffy from the ocean after the latter defeated Krieg. Later, in Thriller Bark, Sanji is revealed to have read about Devil Fruits in his childhood in the North Blue, and states that only the Clear Clear Fruit's power would be worth losing the ability to swim. This means that Devil Fruits are well-known enough to have their own reference materials in the world of One Piece, making the earlier examples of people doubting their existence even weirder.
- The taste of Devil Fruits themselves. Nowadays, they're universally treated as tasting disgusting, but in the early chapters, they were treated as tasting mediocre at worst. When a young Luffy ate the Gum-Gum Fruit, he had no real issues with eating it, simply telling Shanks' crew that it didn't taste that good. And when a young Buggy accidentally ate the Chop-Chop Fruit, he had no reaction to its taste whatsoever (though in the latter's case, it's possible that since he swallowed it whole, he didn't even have a chance to taste it). To be fair, Luffy will eat practically anything even if it tastes bad. See: the cherry pie in chapter 223.
- During the East Blue, the Straw Hats leaving an island with only one or two people aware of their heroics was almost a once-per-arc gimmick. This was pretty much dropped from the Arlong arc on (when Nezumi reporting Luffy's exploits to the Marines put Luffy on the Marines' radar and got him his first bounty), where they're hailed as national (if unofficial) heroes in pretty much every kingdom they visit.
- Luffy's fight with Zoro at Whiskey Peak. It's been made clear that Luffy would do anything to protect his crew and he believes in them completely, so it seems kind of odd now that he instantly attacked Zoro for supposedly killing a bunch of strangers who fed them (who were actually assassins) without even asking him about it first.
- In episode 69 of the anime, Luffy showed no reaction to the Garp's name when Nami read out the newspaper, unlike much later when Aokiji mentioned that he owed a lot to his grandfather. This is justified, since that part in episode 69 was anime-only and Luffy's relation to Garp wasn't revealed yet.
- When Miss All Sunday is sitting on the Going Merry out of nowhere, Sanji and Usopp point their weapons on her head. Sanji, of all people, is pointing a gun at a woman. He does says that he doesn't really know what he's doing and only then realizes that she's a pretty lady, but it's still an odd moment for Sanji, who is known for refusing to harm women.
- Tony Tony Chopper used to look much different back when he was introduced compared to what he currently looks like. He was chunkier, scruffier and had a larger snout; almost nothing like the Ridiculously Cute Critter we know today. Oda has gone on record saying that he used to be very averse to Ridiculously Cute Critters and didn't want to make Chopper one, but changed his mind upon hearing Ikue Otani's portrayal of Chopper.
- The death of the often-forgotten minor character Pudding Pudding in the Arlong Park Arc. Considering an equally unimportant guy like Caribou from the Fish-Man Island Arc can survive having his ship destroyed at the bottom of the ocean, it's kind of odd that Arlong was actually allowed to kill Pudding Pudding (in similar fashion as Caribou to boot, since he sent his ship to the bottom of the sea).
- While the visual cues are only visible to the audience (as Rayleigh confirmed that it's invisible in-universe), Haki had little to no visual cues whenever a character used it before the timeskip. As the series progressed, Haki became a standard ability for any self-respecting strong individual in the New World, and it gained visible effects on usage: Color of Armament has the user coating their bodies with a black material, Color of Observation shows the user’s eyes glowing upon activation, Color of the Conqueror shows a monochrome blast in the anime, and when two people with Conqueror's Haki clash, black lightning surges. The original usage of Conqueror's Haki, by Shanks in chapter 1, was also different: the Sea King he used it on got scared and ran away, but after Haki is properly introduced, victims of Conqueror's Haki are usually knocked unconscious.
- Armament Haki, in it's earliest form, appears to have been intended as a type of psychic and/or telekinetic power. This is best seen when Sentomaru is able to fling Luffy around with no problem in Sabaody, and then again during Marineford when the Admirals stopped Whitebeard's shockwave from hitting the execution platform by gesturing with their arms and concentrating. Nowadays, it's predominantly used as armor to amplify attacks, and to defend oneself. The Land of Wano Arc however later reveals a more advanced form of Armament Haki, that more closely resembles the telekinetic type of power shown earlier in the series.
- Speaking of Haki, Ace being shocked that Teach can touch him now comes across as this because it's since been revealed to be a common for New World pirates to be able to touch Logia Fruit users using Haki, and Teach is an experienced New World pirate. The point is further hammered home by Teach commenting that Ace is probably not used to his enemies being able to hit him. The Ace novels makes it even weirder since they establish Ace himself developed Armament Haki to fight Vice Admiral Draw. There's also no indication Ace could use Haki at the time since he didn't even try to use it on Blackbeard, opting to fight with his Devil Fruit exclusively. Since characters who know of Haki can sense when it's being used, it's possible that he didn't sense any Haki coming from Blackbeard and was surprised by how something other than Haki was nullifying his powers.
- Haki also goes from a rare and mysterious ability to something basically everyone in the New World can use (except Conqueror's Haki), which makes it all the weirder that New World level characters who appeared before the timeskip didn't seem to use it. Mihawk, Doflamingo, Jimbei, Ace, and some Marines who were all later confirmed to be Haki users never displayed any of its abilities pre-timeskip despite later showing to be high level users (though it may be attributed to Haki being invisible pre-timeskip), while Crocodile and Moria, warlords supposedly among the strongest and most infamous Pirates not connected to the Four Emperors, suddenly seem like small potatoes compared to virtually all the New World characters since both are shown to be incapable of using even basic Haki.
- Big Mom. When she was first introduced (in Fish-Man Island, not her silhouette) looked almost like a cephalopod, had acidic saliva, and was seen casually eating a member of her crew (though the victim isn't actually seen and may have been a food Homie in hindsight), but when she was formally introduced, she not only looked completely different, but the saliva thing was gone and she consumed others' lifespan with her Soul-Soul Fruit rather instead of literally eating them. Her personality also changed: on Fish-Man Island she was intrigued or even impressed by Luffy challenging her, and agreed to shift the island's debt to him, but by the time Tottoland came about, she had displayed absolutely none of this honorable behavior, being a bat-shit crazy loon who dismissed Luffy as basically nothing and was enraged that he and the Sanji retrieval team would dare oppose her.
- The first of the Big Mom Pirates to appear such as Bobbin, Pekoms, and Tamago, are not related to Big Mom biologically or through marriage despite calling her "mama", while basically every other member of her crew introduced after was either her biological child or a homie created from her power.
- Kaido was first introduced as a Death Seeker who made a hobby of attempting to kill himself simply to see if he can be killed, traveling to a sky island just to jump off. Later, he's shown to remain in Wano and no mention of his death wish has been made since.
- Kaido was also a lot bigger when introduced, appearing roughly as big or bigger than an Elbaf giant. Later, his height is comparable to Big Mom and he's actually shown to be a hair shorter than Gecko Moria, who's only about knee high to an actual giant.
- One of the first of Kaido's underlings seen is a cyborg named Scotch. He sticks out like a sore thumb compared to the other Beasts Pirate lieutenants because nearly all of them follow a theme of possessing Zoan Devil Fruit powers; in particular all of Kaido's top personnel have Ancient model Zoans that allow them to turn into prehistoric animals, while Scotch has no apparent Devil Fruit powers at all despite being important enough to be in charge of guarding one of Kaido's favorite islands. There are a few other cyborgs in his crew, but none like Scotch.
