A majority of the music from the game are actually songs from all the One Piece: Grand Battle games never released in the US.
Contributed by SOGESNAKE
This is the first and only game so far in any region in which Kuina or Zeff are playable characters. However, both of their movesets are copies of existing characters, which Kuina using Tashigi's, and Zeff using Sanji's.
Contributed by SOGESNAKE
One Piece: Grand Adventure is a sequel to One Piece: Grand Battle Rush! developed specifically for American audiences, and is not available in Japan. It includes content that was cut out of the American release of One Piece: Grand Battle Rush!, which removed characters, stages, and music, most likely because the televised airings of the anime in the US had not revealed certain characters yet.
Contributed by SOGESNAKE
The box art for the game reuses the image of Luffy from the cover of Fighting for One Piece, which was only released in Japan.
Contributed by SOGESNAKE
During localization, everything that referenced the term Marine was changed to reference the term Navy. However, in adventure mode, some characters still make mentions of Marines instead of Navy a few times.
Contributed by SOGESNAKE