Factual error: When the protagonist is looking up the fingerprint (or fingertip...) data in the computer, he gets a match for a New York State Driver license. The document is a clear fake, with no document number (which in 2008 was on the front) and a 10 digits client ID number instead of 9 digits. (00:04:00)
Continuity mistake: As El Camaleon pulls the Cuba Gooding Jr. face off, there's an unshaven neck with a tattoo visible under it. After the cut, Lady Gaga's face (also presumably unshaven admittedly, but not visibly so) comes to light under a mask of visibly lighter skin tone. (00:45:05)
Continuity mistake: After stabbing the bad guy at the beginning, Callahan for some reason pulls back and somehow dives past a door managing to drag in a grown woman who was all crouched down by the entrance. Wonky physics of it aside, the bad guy shoot at him, but shoots just a hole in the door frame. The hole appears to be CGI, and in fact when Callahan shoots back from the bedroom, the hole is gone. (00:01:35)
Continuity mistake: The needle Cheryl's holding goes back and forth from her right to her left hand between shots.