Beware Greeks Bearing Gifts - S1-E12
Visible crew/equipment: As the people of Troy are about to be attacked by the warriors in the horse, the camera pans up to the side of the wall where Deiphobus is talking with another soldier. You can see a crew member crouching down behind them wearing a white and grey shirt. (00:30:35)
Deliberate mistake: During the civilian sheriff's pursuit of the Navy car, the sheriff is occasionally visible in the passenger seat of his patrol car instead of the driver's seat.
Revealing mistake: Right at 40:30, if you look in the top left corner of the LCD screen, you can see a mouse cursor. Six seconds later it starts to move around. It seems like someone noticed and tried to move it out of the scene. (00:40:30)