Continuity mistake: The door to Dexter's apartment opens out toward the walkway. However, in all subsequent episodes the door opens into his apartment.
Factual error: Gay pride flags are visible in a window. The 6 color flags shown were introduced in 1979 (though an 8 color flag preceded it in 1978). (00:30:44)
The Head, the Tail, the Whole Damn Episode - S4-E15
Visible crew/equipment: The scene where Gus is smelling for the first shark and Shawn is 'divining' it. As they round the corner at the dock, a camera and some randoms are visible down the alley for a few seconds. (00:19:00 - 00:23:50)