The following information came from both my own observations, the IMDB trivia page for Romeo + Juliet, and Shakespeare Marketing. There is more information on these pages than what I present here, so I highly recommend you chekcing them out by clicking the links.
Allusions in this film abound. Remember allusions are references to other stories, poems, historical events, people, etc.
At the gas station alone, there are several allusions. Abra, one of the Capulets says, "Double, double, boil and trouble," in a punkish way at the nuns that leave the store. This is a line from Macbeth. When the nuns cross their van to get away from him, the Montague boys are hanging out there singing a song on the radio, "I am a pretty piece of flesh I am." This is not really an allusion since it is a line from Romeo and Juliet, but I thought I'd mention it here. The funny thing is that it should be a Capulet who says this, not a Montague, but in this early scene the Montagues and Capulets have their lines crosses quite a bit.
Also in the gas station is this sign:
This is a mythology allusion. The phoenix is a mythical bird that dies by burning itself and then returns from the ashes. This is also foreshadowing since it gives you a major hint that the gas station will burn up.
Add to that the "Add more fuel to your fire which enforces the foreshadowing and is itself another allusion. This one is a line from Henry VI part 3.
"O that I were a god, to shoot forth thunder upon these paltry, servile, abject drudges!"
King Henry VI part 2.
Sword Series S
"Sir John, I am thy Pistol and thy friend…."
Henry IV, Part 2
The Capulet motto
"Experience is by industry achiev'd"
The Two Gentlemen of Verona
The Montague motto
"Methinks the truth should live from age to age, as ‘twere retail’d to all posterity"
"Wherefore" means "why" and "L'amour" is Italian for "love." O.K., not an allusion, but a clever sign nonetheless.
Prospero Scotch Whiskey
"Such stuff as dreams are made on."
The Tempest spoken by the character Prospero.
The Merchant of Verona Beach
A play on the title of a Shakespeare play - The Merchant of Venice
Out Dann'd Spot Dry Clean
"Out, damn’d spot! out, I say!"
Macbeth spoken by Lady Macbeth when she can't seem to get imaginary blood off her hands.
Shylock is a rich character in The Merchant of Venice.
Note the name of the pool hall. Same as Shakespeare's personal theatre.
Almost everything on these magazines is a quote from some Shakespeare play or another.
This scene is when Mercutio and Tybalt are fighting. There really is a storm coming (a hurricane to be exact) and it destroyed the whole set.
Claire Danes, the girl who plays Juliet, wore a wig throughout the whole movie.
Other actresses considered for Juliet:
Claire Danes got the part, but she had some competition.
Sarah Michelle Gellar
She had a contract with All My Children and that interfered with the filming of the movie.
Jennifer Love Hewitt
The director thought she looked too young to play the part.
She flew to Sydney, Australia to film scenes with Leonardo DiCaprio,
but Leonardo was too tall to fit well with her.
Other Actors that were considered for Romeo
Leonardo DiCaprio was Baz Luhrmann's first choice to play Romeo.
Here is the prologue of the play:
Two households, both alike in dignity,
In fair Verona, where we lay our scene,
From ancient grudge break to new mutiny,
Where civil blood makes civil hands unclean.
From forth the fatal loins of these two foes
A pair of star-cross'd lovers take their life;
Whose misadventured piteous overthrows
Do with their death bury their parents' strife.
The fearful passage of their death-mark'd love,
And the continuance of their parents' rage,
Which, but their children's end, nought could remove,
Is now the two hours' traffic of our stage;
The which if you with patient ears attend,
What here shall miss, our toil shall strive to mend.
Note what is bolded - the movie lasts exactly 2 hours for this reason.