The Penguin's Colin Farrell said even though we don't see it, Oz Cobb sported an anatomically correct prosthetic penis during his nude scene.

Farrell’s physicality matches his minutely calibrated vocal rasp as Oz. He’s not recognizable as Colin Farrell but in this world of deception and shadows, the casting works. And for all the low-light nightclub murmuring going on,

The cast and crew of the new HBO series talk in great detail about how Colin Farrell transformed on-screen, physically and artistically, into becoming Oswald "Oz" Cobbs.