Exterior shots of the stash house that Omar robs show a two story structure, but other shots show three stories with a staircase going up two stories and the hidden guards who ambush Omar being on a third floor.
During the meeting between the Mayor, Burrell and the State's Attorney, Mayor Royce says to Acting Commissioner Burrell "if you want to finish out Walker's term." However, the previous Commissioner was called Warren Frazier (as played by Dick Stilwell in The Hunt (2002))) not Walker.
At 24 minutes and 27 seconds when Acting Commissioner Ervin H. Burrell enters the room he lays down his folders on the table in front of him just as he walks in. In the next shot when he sits down he is seen still holding them in his hands and then putting them down on the table.
During Detective Ray Cole's funeral, the actor (who is supposed to be dead) can be seen breathing as they cut away from his body on the pool table.
At least two observers (possibly crew, or just passersby) can be seen at the end of the street while the gun fight at the drug store house is going on.
When referring to what should be done about a suspect Bunk says "Kofi Bryant and the UN should get a call". Kobe Bryant is the basketball player, and Kofi Annan was the General Secretary of the UN.
Councilman Thomas Carcetti mispronounces his last name. He pronounces it "Carketti", the correct Italian pronunciation is actually "Carchetti".