Accidentally Accurate: Interestingly, the card effect and artwork position of Stoic of Prophecy perhaps unintentionally matches the meaning of the Hanged Man in another way. The Hanged Man in the tarot card is upside down (as cards often are in the anime when characters discard) then the card means what it normally does: sacrifice and selflessness. When the figure in the card is upright (as it would be if summoned) it means an inability to act, which is reflected by this card being weak when on the field.
Bad Export for You: The European releases of the first few Booster Packs were missing several cards. Fortunately, these were restored in later releases.
Many of the more recent Structure Decks are like this, either being edited to remove high-rarity cards, or in two cases scrapping the deck altogether and importing the new cards in them as add-ons to normal sets.
The TCG missed out on the chance to get Dark Magician Girl as drawn by Kazuki Takahashi in the 10th anniversary pack. Justified, however, because Takahashi refused to bow to Executive Meddling to have Dark Magician Girl censored.
Fan Nickname: Japanese fans often called Yugi "AIBO" and the other Yugi "King" (Ou-sama).
Hey, It's That Voice!: David Willis voices both Gozaburo Kaiba and the nameless Rare Hunter in the English dub. Coincidentally, both characters use an Exodia deck (though different versions) and both suffer from the weakness of thinking that having Exodia (or Exodia Necross in Gozaburo's case) is all they need to win.
Keep Circulating the Tapes: Because of some legal issue, it's impossible outside Japan to find any official release of the anime other than the edited dub version. 4Kids attempted to release unedited DVDs of the show, and later put subtitled episodes directly on YouTube, but both of these releases were cancelled, leaving people who don't want to endure 4Kids' edits out of luck if they want to be legitimate customers.
LittleKuriboh has noted that he doesn't abridge "Season 0" because high-quality footage of that series is impossible to find, but of course it has to exist somewhere out there because there's many fansubs of it. (He was right.)
Those fansubs were from old TV recordings. Hardly "high quality."
In the Card Game, there are some cards that just can't be bought normally, first hand as in the way they were meant to be; the most famous example is the first edition of the 3 Egyptian God Cards: foiled, shiny and Colour-Coded for Your Convenience, these were packed with the GBA game Yu-Gi-Oh! Reshef Of Destruction; people went crazy for this game just to get the cards, a great deal of the copies sold for this game was due fans wanting the cards, eventually retailers came to know that some people just bought the game for these cards, so they would gladly put a reminder for used copies Does Not Contain The Limited Edition Cards!, people on eBay followed suit as gullible fans also thought that buying a $20 copy of the game would grant them shiny and exclusive cards that were sold for about $100 separately.
Name's the Same: The name Paradox has been used at least three times; the Labyrinth brothers Para and Dox, the Grandpa lookalike in the Reshef of Destruction game, and the antagonist of the Bonds Beyond Time movie.
Hierophant from the "Prophecy" archetype has the same japanese name as "Hanion, the Time Lord".
Fire King Avatar Yaksha is the second card that is a reference to Yaksha; the first is "Yaksha". Interestingly, these two cards have the opposite Attribute ("Fire King Beast Yaksha" is FIRE; "Yaksha" is WATER).
"Gimmick Puppet Gear Changer"'s name is similar to "Gear Changer". Also, both cards' are gears with effect that involves changing Levels.
Hieratic Dragon of Nebtet comes from the Egyptian God, Nephthys; that name is shared with "Sacred Phoenix of Nephthys" and "Dark Nephthys".
The Blue-Eyes Shining Dragon was released as a promo for the movie in 2004. The card required to Summon it, the Blue-Eyes Ultimate Dragon, wasn't released until over a year-and-a-half later. Though both were available in Japanese, OCG cards are not allowed when playing the TCG.
Recent TCG sets have included more cards than the corresponding OCG set- some of these are cards that were previously OCG only, while others are cards that are exclusive to the TCG. In turn, TCG only cards have recently begun to be released in the OCG through the Extra Pack sets. Eventually the two card pools may become equal...
Sometimes this applies to the video games as well. Tag Force 6, hotly anticipated by some as the first video game to feature Xyz cards, was not released outside of Japan.
Word of God: Two, as a matter of fact; until 2008, card rulings were given by both Konami and UDE, and they didn't always agree with each other. Many cards actually have different rulings for the TCG and OCG versions of the game because of this.
It's notable that in case of disagreement between the companies, it's rare but not impossible for the TCG's claims to gain worldwide sway in terms of deciding how cards actually work once word of the disagreement gets across the Pacific - and any cases where the TCG's claim does stand ultimately stand because the OCG and TCG management departments agree that "that works better for our purposes." Ultimately, the game's management (at least in some senses, including rulings) considers YGO to be 1 worldwide game with different names in different regions; and the OCG is the origin point, thus it's the locale that holds sway a good chunk of the time. Points of disagreement that aren't ironed out are simply points of disagreement that either went unnoticed or were noticed but deemed unimportant; but while a disagreement DOES exist, you are required to follow the orders of your own jurisdiction, regardless of whichever side you think will "win" the argument.