Created in 1996, Yu-Gi-Oh! has gone on to become one of the most popular animes of all time. With iconic characters like Yugi Muto, Seto Kaiba, and Joey Wheeler, these teenage duelists took on the world with their cards and close bonds. However, in their wake of monsters, spells, and traps, there have been tons of storylines that the series introduced only to leave them unresolved.
For today's list, we're going to largely focus on the original series but we will throw in a couple of entries about Yu-Gi-Oh! GX, the sequel to the original series. It's time to nitpick some plot details!
10 Mai Oh Mai, Where Did You Go
Joey Wheeler's rival turned friend turned rival, Mai Valentine really gets the short end of the stick throughout the series. Not only does she lose most major duels she has on-screen, but her heel turn in Season 4 of the anime ignores her character development in earlier chapters.
Worst of all though is that in Season 5, we don't see her at all! After she loses her soul and is subsequently saved by the heroes, we don't see Mai in any meaningful capacity. In the original Japanese anime, we see a brief image of her tag dueling with Vivian Wong against the Paradox Brothers, but that isn't satisfying at all. What became of her and Joey?
9 For The Fate Of Red Eyes
Joey and Yugi don't duel regularly; however, when they do, it's often an emotional high point of the season. After Joey was one attack away from beating Yugi in the Duelist Kingdom tournament and then forced to duel his best friend to the death in Battle City, the two decided to fight for the fate of Joey's Red-Eyes Black Dragon in the final episode of the Battle City arc.
Having lost the card in a match against The Rare Hunter, Joey told Yugi to keep hold of the card until one day he earns it back. When Season 4 begins, we see that Joey has the card back... but we never see their duel! We can always assume that Joey beat Yugi for the card, it's also possible that Yugi gave Joey the card regardless of the result. This was a tease we could have done without.
8 Dungeon Dice Monsters
In the final set of episodes of Season 1, the gang meets Duke Devlin, the upstart game shop owner and creator of what Konami surely meant to be the next big thing: Dungeon Dice Monsters. However, as Yugi defeats Devlin at his own game on live television, Devlin believes that his game is ruined. That said, the match doesn't seem to sour Devlin's deal with Industrial Illusions as they take the game worldwide anyway.
Great, but what happened next? Well, your guess is as good as ours! While Devlin does show up many times afterward, nothing about his invention is really brought up again.
7 Pegasus Is Healed
After Pegasus is defeated by Yugi in the finals of Duelist Kingdom, he is ambushed by Yami Bakura in his quarters and has his Millenium Eye stolen. In the manga, this is the end for Pegasus as he is brutally murdered; in the anime, he falls into a coma.
For the entirety of Battle City and the Virtual World arcs, Pegasus never gets mentioned but then when the Waking The Dragons arc begins, he suddenly recovers and provides Yugi with a card that proves crucial in defeating Dartz. We never really see how or why Pegasus recovered from his injuries. Call it the power of the plot we suppose.
6 Is Bandit Keith Dead?
The brash American duelist, Bandit Keith may not have any magical powers but he still proves to be one of the most dastardly villains in the show's history. From trying to trap the gang in a cave and cheating in all his duels, Keith is a trickster.
After he's booted from the Duelist Kingdom island by Pegasus, Keith falls under the control of Marik Ishtar and is last seen losing his mind as he flees from the burning warehouse where he dueled Yugi. This would be the last time we see Keith... sort of. He does make an appearance as a "lost soul" seeking revenge on Atem in Season 4. Aside from that, we don't know what became of this villain.
5 Who's That Stranger?
Once the original Yu-Gi-Oh! anime concluded, fans were quickly dealt a new series in the form of Yu-Gi-Oh! GX. While its reception was mixed, it certainly got off to a shocking start by having what is alluded to Yugi appear to give the new protagonist Jaden Yuki a "Winged Kuriboh" card. The only question is, was it Yugi or Atem that appeared to Jaden?
In the original Japanese version, the person is definitely Yugi, as he also appears in the Japan-only Season 4 (we'll get to that). In the English dub, the character speaks in the voice of Atem. This begs the question: Did Jaden meet Atem or Yugi in GX's pilot?
4 How Did Yu-Gi-Oh! GX End?
As far as English speaking audiences knew at the time, Yu-Gi-Oh! GX ended with Jaden bonding with Yubel and closing the book on her evil ways. But there was a fourth season of the show which dealt with the villain Nightshroud returning to plunge the world into darkness.
A true pain in the deck slot for Yu-Gi-Oh! fans, Season 4 was never localized for English speaking audiences. Due to a desire to begin production on the translation of Yu-Gi-Oh! 5Ds, 4Kids Media chose not to dub Season 4. Consequently, we never got the dream match of Jaden Yuki vs Yugi Muto.
3 The Millennium Necklace Can Teleport
While he begins as a minor antagonist in the first few seasons, the evil spirit of the Millenium Ring ends up being the final villain of the original Yu-Gi-Oh! series. However, he is also a complicated character with numerous powers that seemingly come out of nowhere.
One of the biggest WTF moments comes in Season 1 when Tristan manages to incapacitate Bakura and then throw the Millenium Ring into the forest. However, the ring just reanimates itself onto Bakura's neck in the next episode. The answer? Probably that it's magic and we're asking too many questions about an anime meant to sell trading cards.
2 Who Won The Yugi Vs Jaden Duel?
This is the dream match everyone wanted to see. The protagonists of their own respective series, Yugi Muto and Jaden Yuki faced off in the finale of Yu-Gi-Oh! GX. Does the journey getting there make much sense? Not really. Does the audience care? Not really.
The duel is one for the ages, with Jaden busting out his classic Elemental Hero monsters rather than the Neo-Spacians he used for much of GX; in the meanwhile, Yugi utilizes all the classics like Dark Magician and Slifer The Sky Dragon. Disappointingly, however, we don't get a clear winner. Instead, the series ends with Jaden attacking Slifer The Sky Dragon with Elemental Hero Neos. While real-world dueling logic shows that Yugi would win based on the attack strength of the monsters in battle, this is Yu-Gi-Oh!. Anything can happen.
1 Atem's Return In Dark Side Of Dimensions
Some fans may have missed it, but there was actually a new Yu-Gi-Oh film released in 2017 based on the original series. Titled Yu-Gi-Oh: Dark Side Of Dimensions, it features Kaiba attempting to bring back Atem into the real world and a new threat named Aigami emerging.
While the movie is pretty confusing unless you're up to your neck in the franchise's lore, the biggest question mark comes at the end when Atem returns to save the day from the evil of the Millenium Ring. This flies in the face of the rules the series established long ago. It seems like Kazuki Takahashi is telling audiences "screw the rules I know you want nostalgia."
Unless we get a follow-up, it seems like Atem's brief return to our world left behind tons of questions.