Beta pictures and videos show Giorno with a different model, with differences particularly visible in his face. He was polished before the game's release.
Beta pictures of the game have Koichi Hirose with Echoes ACT3 as complete models, but Koichi was dropped before the game's release. Should he have been playable, Koichi might have fought against Giorno and/or participated in the Black Sabbath battle.
"Jean Pierre Polnareff's" theme, is an orchestrated version of his previous theme from JoJo's Bizarre Adventure (1998).
The game was originally going to have an international release, but was eventually cancelled due to unknown reasons. It's believed the cancellation was due to copyright issues.