TAG Heuer Carrera Calibre 1887 Chronograph - Lee Byung-hun - RED 2
The watch seen in the film has a black dial, 41mm steel case, steel bracelet and is model reference number CAR2110.BA0720.
Interestingly, the design of this 1887 model has been changed a few times in the year 2010, which is excellently explained and shown in this artlcle on Calibre11.com and this follow-up article. Basically, the changes are most visible in the tachymetre indication and the logo. The watch seen in the movie RED seems to be the Version 2 model from 2010, where there is no tachymetre indicator and the logo is placed slightly higher then the Version 3 model (compare watches on the images on the left).
If you want to buy this watch online, make sure you see a photo of the actual watch to know for certain which model you are getting.