Yakuza: There's an old saying - For want of a nail...the horseshoe was lost. For want of a horseshoe, the steed was lost. For want of a steed...the message was not delivered. For want of an undelivered message...the war was lost.
In the disco scene, the DJ is playing music, but the Pioneer decks and the DJ Mixer are not even turned on, as no lights are showing.
When Sean is learning how to drift at the docks, the fisherman that comments about his drifting is actually the real Drift King, Keiichi Tsuchiya. The comments about betting on the '72 Skyline and '86 Corolla are throwbacks to him as well as the Skyline was his first drift car and the Corolla was one of his favorites.