Layer Cake (2004)

Revealing mistake: When Gene's bodyguard (the one with the moustache) shoots Slasher and Duke, just before Slasher is shot the bullet hole effect is visible on her forehead (sightly concealed by make-up) just before the actual 'shot'.

The Duke: Don't you fucking talk to me like I'm some kind of mug. Don't you fucking talk to me like that.
XXXX: Duke, don't take this personally. It's business. Now, you want to know how much these pills are worth?
The Duke: Yes. Fucking. Please.
XXXX: Now just because you pay a fiver a pop down the local cattle market, don't, for fuck's sake, think these pills are worth millions. They're not. We've got to find someone to buy these pills and they've got to split them into parcels, of say 100,000. They've got to find these people. It's hard work.
The Duke: Oh, you'd give a fucking aspirin a headache pal.

Trivia: In the final scene were XXXX is in the Park club dining with Trever, Morty, Gene, and Clarkey there is a shot outside the room looking in where XXXX is standing and the others are raising their glasses to him. This is similar to the final scene in 'The Godfather'. This is said during the director's commentary.

Question: Why is there a 4 in place of an 'a' on the title? It says "L4yer Cake".