Musically my favourite scenes are those featuring the radio DJ who broadcasts a coded commentary on the gang battles with lines like 'All right now for all you boppers out there in the big city, all you street people with an ear for the action' before playing Nowhere to Run as a threat to the Warriors.
Then there's the scene where the Warriors are enticed into the club house of The Lizzies, an all-women gang who promise 'Let's party a little, get something going'. You don't need a PhD in queer studies to work out that Lizzies suggests 'Lezzies', with women dancing together to "Love Is A Fire" by Genya Ravan. Of course the welcome is a trap and as the women pull out their weapons a hapless warrior shouts 'The chicks are packed'. The film is loosely based on an ancient Greek story, so The Lizzies also stand for the Sirens.
Update: As mentioned in the comments, a sample from the film features in the mid-1990s house track Can You Dig It by Mark the 909 King (sample kicks in at about four minutes):
The Can You Dig It sample comes from a speech by gangleader Cyrus early in the film, where he calls for the gangs of New York to unite and take over the city:
This speech is also sampled in Can U Dig It? by Pop Will Eat Itself