When Cal is driving to Stephen's office near the end of the film, it shows him driving without anything on his right hand, which was heavily wrapped up in obvious white bandages in both the scene before and after his drive.
Stephen Collins first appears to Cal McAffrey's apartments unshaven. Then we see him looking out from the window and is totally shaved. When the camera is on him again in the apartment he is unshaven again but not in the same length as before.
Before Della runs after Cal in one of the office scenes near the end, she is wearing the pen necklace he gave her. It was shown that she just got up and ran after him, but the next time we see her she is not wearing the pen necklace.
After Della Frye abandons the phone call from McAffrey during the night, she throws her mobile phone onto the night stand. The phone changes its position twice during the subsequent shots.
Midway through the movie, when a character takes the Washington Globe off of a news rack, it is a tabloid. In the final scene, it's a broadsheet.
A key piece of evidence is obtained by watching surveillance video from the Metro station. While there are cameras in the Metro system, they are on a closed circuit used only by station managers to observe the station. They are not recorded.
When the DC Police detectives descended en masse on the newspaper's offices, they had FBI badges on chains around their necks. DC detectives wear DC police badges.
When he says he was 17 years old and deployed this cannot be true. Its stems from the the Child Soldier Protocol from the United Nations which states parties shall take all feasible measures to ensure that members of their armed forces who have not attained the age of 18 years do not take a direct part in hostilities. Therefore, the US specifically does not allow anyone under 18 to deploy.
The District of Columbia license plates on Cal McAffrey's Saab start with N. In 2009, the highest letter in the alphabet for these plates was a D or E.
When Anne is looking out the window of her home to look at the news vans across the street, there is a WHYY microwave truck between the other vans. WHYY TV has no such trucks.
In the final scene of the printing montage at the end, the sign on the side of the truck says "Washington Post".
In the photograph that shows Sen. Stephen Collins with his fellow Gulf War soldiers, it is obvious that Ben Affleck's face has been edited into the photo.
McAffrey's car is shown to have a CB and at least one other radio, yet there are no antennas on his car.
Crystal City (the stated location of the bad guy's apartment house and location of the chase in the underground parking garage) is in Virginia. DC Police (MPDC) would not respond to calls there (unless under Mutual Aid circumstances, a super rare thing)
Sonia leaves her apartment in Adams Morgan in DC and walks to the Metro station in Rosslyn, which is in Virginia more than 2 miles away, on the Blue/Orange Line. The closest Metro station to Sonia's house is probably Woodley Park/Zoo on the Red Line.
WHYY is a non-commercial educational TV station licensed in Wilmington, Delaware, and a PBS station in Philadelphia, Pennsylvania.
While difficult to measure accurately, the film takes place over too short a period of time, for the action involved. From the dates on the newspapers, the timeframe appears to be 3 or 4 days maximum. Yet the evolving nature of the story, the amount of time required to track down leads, etc., probably would require much more time.
Characters make references to Metro Police when talking about the Metropolitan Police. Metro Police are Metro Transit Police, and work for the Washington Metropolitan Area Transit Authority (WMATA) in and around Metro stations. Metropolitan Police are the Metropolitan Police Department (MPD) of the District of Columbia, and they work the streets of Washington, DC.
Bingham wears his ACU blouse the wrong way, with the collar up. Typically it is worn with the collar town, a veteran soldier like him should know that.