Character mistake: When Mr. Brooks and Marshall hack into the police database and are looking at detective Tracy Atwood's financial records there is a screenshot of the computer screen showing some very terrible spelling.
Factual error: The license plates on Dan's car are very inaccurate fakes. The colors especially are way off. Certainly, the makers may use a fake sequence of characters the same way "555" phone numbers are, but the styling of the plate should look right. Real NJ plates are a pale yellow along the top 1/4 that fades to a very pale tan by halfway down. Dan's plate is a bright yellow (nearly orange) at the top and the rest is white. The numerals are also the wrong typeface. The mistake is made more obvious by the fact that real New Jersey plates are seen in the early portion of the film on other cars.