Homecoming - S3-E5
Visible crew/equipment: When Buffy and Faith are in the library, a person's arm wearing a white shirt can be seen on the left side of the screen behind Buffy in one shot.
Band Candy - S3-E6
Continuity mistake: The tattoo on Giles' arm is reversed compared to the way it was facing in the "Dark Age" in season 2.
Visible crew/equipment: While Buffy, Giles, and the gang are in the library fighting the demon that came out of the Hellmouth, the camera zooms toward the door that leads into the hall, where you can see Xander being chased by the dead guys. As the camera zooms in closer towards the round window in the door, you can see its reflection in the glass when the strobe light flashes. (00:36:10)
Chosen answer: It is classic vampire mythology.
Twotall