The music track is titled Green Greens from the Smashing.. Live! arrangement of Super Smash Bros. Melee's soundtrack.
As stated above, Dream Land is the generic term used for Kirby's homeland, paralleling Mario's Mushroom Kingdom or Link's Hyrule. Whispy Woods is a common boss, and was the first boss of the entire Kirby series. A wind attack is used by Whispy Woods in the Kirby series; however, this was not in Super Smash Flash due to there being no hazards in SSF. The design of Whispy Woods is possibly based on his second phase in Kirby's Dream Land 3.
The track that plays in this stage was not originally played on the original version in Super Smash Bros.; instead, a remix of Gourmet Race is the main track.