Continuity mistake: Episode "Heartland": In the first five minutes of the show, after the guys are beaten up in the alley, when the black guy is laid down on the ground there is a blood stain on The Wall, behind where he was standing. When the other guys go to the white guy's aid the blood stain is gone, for about 3-4 shots. When the NCIS team is there gathering evidence the blood is back on The Wall.