CensorshipThe U.S. release of the game was partially censored. Originally, Lammy died at the beginning of Stage 6 by slipping on a banana peel dropped by P.J. Berri (from PaRappa's gang) and ended up in Hell, where Teriyaki Yoko would agree to resurrect her if she played in her performance. In the U.S. version, the whole scene was changed to Lammy getting her belt caught on the door of Paul Chuck's shop and getting hurled to an island, where Teriyaki Yoko needs for her to play before she'll get Lammy off the island. Chop Chop Master Onion's lyrics in his song were also changed to reflect this alteration.
PackagingThe original Japanese release has curious packaging: the jewel case is packed backwards, and there's a hole cut in the inlay though which the disc can be seen. Another game with similar packaging is Vib-Ribbon, which also happens to be developed by NanaOn-Sha.
PaRappa's songsCompleting the game unlocks PaRappa as a playable character, complete with his own versions of each song. However, the first stage with Chop Chop Master Onion (Lammy's dream) isn't available to play with PaRappa. Curiously, a version of this song performed by PaRappa appears on the game's soundtrack, though unlike the other stage music, PaRappa's version is not remixed at all and simply swaps out Lammy's guitar for PaRappa's rapping.
SoundtrackAn official soundtrack featuring all the music from the game, including the cutscene cues and PaRappa's tracks, was released by Sony in November 1999.
Information also contributed by 雷堂嬢太朗 -raido.jotaro-