1. In the Japanese, although Yugi clearly knows about 'the other me' he says that they're talking for the first time during the Pegasus duel. What he actually says is "I screamed and screamed, but you could never hear me before!"
Japanese Yugi is so cute I want to die sometimes. In the English, it seems like Yugi and Yami talk often, or at least have already talked at this point. The English indicates they are cooperating to duel, while Japanese Yugi says "we've been taking turns living." the Mind Shuffle is the first time they really talk to each other.
2. In the Japansese, Yugi calls Yami just "the other me" (mou hitori no boku), and Yami calls Yugi either a more arrogant form of the same thing, or just "aibou", which is like the cutest word in the japanese language. When he tells Pegasus that his aibou has more courage than Pegasus ever will, I died a little.
Apparently in the English, however, Yugi asks Yami his name at this point (which is strange if they've been talking, isn't it?), and Yami offers up "Pharaoh, Yugioh (wtf? although in the Japanese, Yugi's grandpa calls Yami this), and Yami." And then Yugi actually calls him "Yami" to thank him. Nobody ever calls Yami Yami in the Japanese, although they do refer to the other Bakura as "the Dark (Yami) Duelist" sometimes.
It's easy to see how "Yami" and subsequently "Hikari" come into fan usage though, because i've heard the phrase "Yamito Hikari" about a billion times at this point, and that's how the whole show starts initially, with a narrator telling you that Yugi is a young boy with both dark and light (yamito hikari) in his heart.
3. Dark Bakura rips the Millenium Eye out of Pegasus's head, then freaking licks it. it's SO GROSS. EW. yay. They edited that shit out of the US version for SURE.
I also really love the way Honda throws the Ring into the forest, and then it just comes back with no explanation. Bakura is love all the way around, really, and I love both Bakura and Yami Bakura's voices.
4. And interesting change happens when Yugi and Yami hi-five at the very end of the Duelist Kingdom arc; In the English, Yami and Yugi's hands pass through each other.
What's edited out from the Japanese is the sound effect of Yugi and Yami's hands slapping. They can touch! At least within the confines of the Puzzle/Yugi's mind.
5. Honestly, the stuff they feel the need to edit out for the US version is bizarre. Joey running off to take a pee in the wood? okay, that's a little vulgar, i suppose...The face that Anzu makes Bakura and Honda blindfold themselves before she climbs a rope above them in her skirt? Come on now, that's common sense!
Shoving the Millenium Eye into Pegasus's eye-socket? that's just...actually, I kind of wish I hadn't seen that...I bet a lot of Malik's stuff will have been edited out when i get there, too, since the recipe for the sennen items is like burned into his skin.
What kills me is how hard they try to edit out Yugi and Yami's...well, everything. From the touching, which i already mentioned, to the crying at the thought of being separated, to Yami swearing he'd rather lose all his memories than be separated from Yugi...there's some creative editing going on, seriously.
but my favorite is still the loss of all the guns, so in the American version it looks like Kaiba takes one look at the guys pointing their fingers at him, and leaps out of the window for no particular reason...
6. Surprisingly, Pegasus's explanation of how Duel Monsters and taking over Kaiba Corp. will somehow bring back his dead girlfriend makes even less sense in Japanese than it does in the English. In fact there really isn't any explanation at all, nor is there one about how the Eye would help him see the dead girl at all.
In the English they blather something about combining the Millenium magic with Kaiba's new dueling imaging technology, which...okay, it still doesn't really make any sense if you are trying to bring back the dead, but whatever. Pegasus has a duel monsters card with Cynthia's picture on it, so maybe he really is going to try to make her appear with Kaiba's system.
In conclusion: Kaiba and Mokuba=siblings make everything better, and Honda and Jounouchi=so doing it.