Other mistake: When Will Smith checks into the hotel and his credit cards are invalid, we see that the time is 5:38 and it is daylight outside. The only problem with this is that it is supposed to be around December given all the Christmas decorations. It would be dark then in the Baltimore, not soaked with daylight.
Revealing mistake: Near the end of the film, after the shootout, there's a shot with the camera zooming in on a newspaper at Will Smith's front door. If you pause it right once the headline fills the top of the screen, you'll notice all the paragraphs are just repeated, word for word. Additionally the word "received" is misspelled.