If you’ve been following the entertainment news lately, you may have overheard a little diddy about Jake Gyllenhaal punching a mirror. While filming Dan Gilroy’s Nightcrawler, Gyllenhaal became so wound up in a scene that he punched a mirror hard enough to require an emergency hospital visit and a few stitches. When we caught up with the actor earlier today to talk about his heroically damaged performance as Detective Loki in Prisoners, we had to ask about the mirror and his hand, which is still bandaged up.

“We were working a scene and it was an intense scene, and I just went for it,” he told us. “It’s going to be in the movie, too, which is pretty awesome. The feeling that you left it all out on the field, ya know? That you even put a little of your own blood into a project.”

In the film Gyllenhaal plays a young man caught up in the seedy, underground world of freelance crime journalism, and while his mirror-punching exploits will indeed make it into the film, he added that you may not see his character punch the mirror in the shot, but you will see it shatter.

“It’s so hard to explain this character,” Gyllenhaal said. “He’s all over the map in this way that is so fun to play. We were experimenting a lot because it’s such a brilliant screenplay — probably one of the best I’ve ever read. Dan Gilroy wrote it, and [the character] is sort of a modern version of a real entrepreneur. This sort of personification of this idea that success is the ultimate goal regardless of anything. He’s charming, and at the same time calculating. Why he is all these things is definitely underneath that [mirror-punching] moment in a way, but he’s just so complex. It was real fun to play as an actor.”

Nightcrawler adds to a long list of edgy thrillers the actor has found himself involved in as of late. Find out why he’s so turned on by these dark, intense roles when our full interview goes live on Monday.