After interviewing one of the victims at the hospital, Dr. Linda Kimura tells Dr. Spencer Reid that before death, the other victims exhibited aphasia due to the impact of the anthrax on the parietal lobe of the brain. The type of aphasia shown, fluent aphasia, where the patient combines unconnected words incoherently, is usually due to damage in the temporal lobe. Damage isolated to the parietal lobe might result in some minor language difficulties, but would not likely cause aphasia.
The train that pulls into the station (filled with passengers) has a "Not in Service" message on its display.
About 34 minutes into the episode a map of the DC metro system is supposedly visible on a computer screen. The map is not a map of the DC metro system.
There is no Metro station in Frederick, Maryland. Although the DC Metro system runs into the immediate suburbs, Frederick is almost 50 miles outside the District and the Metro only runs about 25 miles out at the furthest. Frederick is served by a MARC Commuter Rail station, however.
Hotch and Morgan were driving to the Frederick Metro train station to apprehend the unsub but before they got to the station the scene cut to an image of the New York City 59th street (N,R,W,4,5,6) subway station to help establish the location not a DC Metro station.
Palm trees could be seen in the rear view mirror as the team travels from Washington D.C. to Frederick, MD.
The area in and around Annapolis, MD, is completely flat. The park in the opening scene was at the base of a steep hill.