The movie star had to have "numerous" stitches in his hand, after he cut it during filming.
"While Jake was filming an intense scene... his character purposefully banged his hand into the mirror," said his spokeswoman Mara Buxbaum.
"Unfortunately the mirror accidentally broke, and Jake's hand was badly cut up," she added.He received numerous stitches at the ER and was released a couple hours later. He already returned to set for work."
In the film, Gyllenhaal plays a freelance reporter investigating Los Angeles' crime underworld.
The 32-year-old has lost a lot of weight to prepare for the role.
His most recent film, Prisoners, topped the US and UK box offices in September. It also features Hugh Jackman and centres around the story of two girls who are kidnapped.
