Factual error: In Season 4, episode 1 "Mayhem", Morgan is following a suspect into the subway tunnels. As he is coming around a corner, you can see the tracks behind Morgan. The tracks are three straight pieces of track making a corner. There is no way a train can make a corner on straight tracks. There should have been curved tracks.
Continuity mistake: In episode 13 from season 5 "Risky Business", in the end scene a shot is shown of the FBI airplane in mid air. The airplane shown is a Gulf Stream V; which has a very distinctive nose. After the scene inside the airplane; another shot is shown of the plane's exterior, however all of a sudden they fly a Gulf Stream 100, which is a significantly larger plane and a very different design.
Factual error: Empty Planet Episode: In the opening sequence a bomb is detonated on a bus in Seattle, in the vicinity of the Seattle Center/Space Needle. Right after the explosion, as people are moving towards the now smoking bus you can see a palm tree in the background. There are no large palm trees in metropolitan Seattle and absolutely none in this area.
Other mistake: Demonology, Season 4, Episode 17. Prentiss pulls up to a bar and the shot shows her looking out of the car window. "BAR" is shown reflected in red on the car window, but it is readable from left to right under the closeup of Prentiss's face when we see her. The reflection of "BAR" should have been backwards since it's a reflection of the sign on the building.
Continuity mistake: The BAU has its 'own' airplane in use at the FBI. However the type of plane used varies between episodes and even within an episode (and even for at least one episode within one shot; see previous post). Although it would be likely for the BAU to have one dedicated airplane at least within one episode, it could be they time-share and so different planes are used. No matter what plane they are using, one thing never changes and that's the interior of the planes. So even when a different type of plane is used (e.g. Gulf Stream V vs. 100), the interior remains the same.