Just got back from my local JP screening, which had subtitles btw! So as to how different the movie is compared to the English version…not all that much. Well at least in terms of scenes, content, and music anyways. I'll just over the main differences off the top of my head from what I remember:
- All the licensed music is still in and the exact same as the ENG version.
- All the scenes and content is the same. No extra easter eggs or extended scenes
- More grunts and sounds where the English version would generally have silence. Some examples, when Bowser's fire is is destroying the castle and you see the reflection in Kamek's glasses, Kamek does a little evil laugh. He also makes sounds as he summons the ice staircase for Bowser, who also makes exclamations as he destroys the ? block.
- The Mario Bros rap commercial is fully localized and the JP VAs say "Itsa me Mario! Anda me Luigi!" at the beginning.
- Jump-man is also voiced by Charles Martinet and he speaks Japanese as well! He says, "Zen zen, itsa perfect!" (zen zen - not at all).
- The "another castle" joke is fully in English by the Toads!
- Mario does a lot more "Bing bing Wahoo!" and "Hoohoo!" throughout the movie when doing anything athletic, like during the training scene.
- DK is also pretty funny and I would say is more energetic than Seth Rogen's DK. During the DK Rap section, he says, "AI AMMU DONKI KONGU"
- The blue shell koopa yells, "BURUU SHERU" when launching his attack.
- Various other puns and wordplays changes as expected
Overall, it was more similar and different than I expected! I think it would be good for a repeat viewing, but not necessarily a first. The mouth flaps and various body movement flow better with the english dialogue, but I still thoroughly enjoyed it as much as the ENG version.
If anyone has any other questions about more specific things or whatnot, feel free to ask!