Willem Dafoe: [detective] When I entered the movie I remember they were already in production…When I arrived for my first scene with Christian Bale, he was fantastic. And I think he’s excellent in the movie. It’s one of his best roles. He was like a machine. And I mean it in the best way…His rhythms, his clarity, his control were just incredible.
Mary Harron: [director] We were filming the business-card scene [transcript] and I remember that Josh Lucas and Justin Theroux came up to me after one of the takes and said he breaks into a sweat at the same time… every time.
Matt Ross: [who plays co-worker Luis Carruthers] With the business-card scene, I think we all knew we were participating in something that had the potential to be iconic.

Guinevere Turner: [screenwriter] …A cool thing that Mary told me relatively recently is that in the scene where the detective that Willem plays and Christian are having lunch at Smith & Wollensky’s—and it’s really tense, and Bateman’s sort of losing his mind—she directed Willem to do several takes where he was sure that Patrick had done it and then several takes where he absolutely didn’t think he’d done it. And then she intercut the two styles. That, I think, is genius.
W. Dafoe: I remember her telling me to play it those different ways. And then she cut it together in a way that was ambiguous where she kind of had her cake and ate it too…That lifted up the scene.
M. Harron: I’ve done that with a few other things…when you’re really on the edge of ambiguity, when you’re not sure what a character’s motivation is.