When Spike says "Free your mind and the rest will follow" when talking to Jet about some life coach it's a possible reference to lyrics from an En Vogue song. The reference is actually to a Parliament/Funkadelic song which En Vogue got from them. "Free your mind and your @ss will follow"
During the gunfight sequence, Spike takes cover behind a monument to the victims of "Earth's first astral gate accident". This is a reference to the original Cowboy Bebop episode "Sympathy for the Devil" (Season 1, Episode 6), where the astral gate accident was the source of the main antagonist's unnatural longevity.