admin edit: SPOILER ALERT
I caught that when I saw it today. Good stuff, I like when I notice allusions.
Anyway, this movie was very engaging; I had sweaty palms the entire two-and-a-half hours. Everything seemed to be at the top of their game: the writing, the photography, the performances, the editing, the sound/music. A nearly perfect stylish thriller. Moreover I found some interesting ideas to be had in it that I'm thinking about: communication without seeing or even hearing (cell phones/texting), especially that moment when Sullivan calls Costigan's phone and neither speaks but so much is still conveyed; the concept of "family," whereas both protagonists had none but found it in Costello in two very different ways (of course, Costigan's relationship with Costello is probably not meant to evoke the same feeling), and in Madolyn, and Costigan in Queenan; the sheer proclivity of headshots and bloodspatters; the idea of what a rat is...etc. Very good, in my opinion; will no doubt make it to my end of the year list.
Another question about the end: were those french bagels (croissants?) that fell out of Sullivan's bag after Dignum shot him?