Colin Farrell is in The Batman as the Penguin. He’s been promoting the movie and his name even appears prominently in the credits. But we never see the actor we all know and love on-screen. At least in any recognizable sort of manner. It turns out the Penguin makeup job was so convincing one of Farrell’s costars didn’t realize it was him.

The  After Yang actor plays Oswald “Oz” Cobblepot, a.k.a. the Penguin, one of crime boss Carmine Falcone’s associates and operator of the Iceberg Lounge. Several of Farrell’s scenes feature other Gotham City criminals like Falcone, played by John Turturro. Before the film’s release, Farrell’s transformation into the scarred mobster was a major talking point. But it was apparently so convincing in person that Turturro didn’t realize he was staring at Farrell.

The actor told   The Hollywood Reporter“I had no idea it was him. I just thought he was some rough-looking guy. I was just staring at him. It was pretty incredible.”

Colin Farrell
Warner Bros.

Interestingly, Matt Reeves revealed that when Colin Farrell was cast as the Penguin, he was never supposed to be buried under makeup and prosthetics. Reeves told  Variety he envisioned Oz as something of a Fredo-like character (John Cazale’s character from The Godfather) in The Batman‘s universe. He was already working with prosthetic makeup artist Michael Marino on designing the right Penguin-esque nose for Farrell. However, the prosthetic makeup look soon expanded after Farrell, who’d gained weight for a role, told Reeves he needed to lose it for his own health reasons.

Obviously, The Batman isn’t a fantastical superhero film. It’s a very grounded, street-level look at Gotham City and its inhabitants. So its villains couldn’t look cartoonish. Luckily Marino’s Penguin design fits in with that grounded look Reeves envisioned while allowing for a very dynamic performance from Farrell.

Warner Bros.

But while Farrell is under a lot of prosthetics and Batman himself hides behind a cowl, Carmine Falcone is also hiding behind a mask. Turturro told The Hollywood Reporter that he wanted the mob boss to have a mask of his own. For Falcone, it’s the tinted glasses. He said, “I thought, ‘I need a mask.’ And then I went to the lady where I buy all my vintage glasses and I found these glasses [worn in the film], and Matt loved them. Because a lot of those guys did wear dark glasses when they testified.”

It’s a small but very telling accessory. One that adds to the air of menace and destruction around Falcone. Even if, as The Batman suggests, his reputation is just partially what it is—an unsubstantiated reputation.