When Willow "magics" a book at 21:17, you see it slide out on its shelf as she gestures with her hand, but the subsequent shots in the sequence do not match its motion, so you see it slide out a second time in close-up and then see it slide out a third time in the background as she walks away.
At 7:15, when the camera tracks down the hallway past the open door to Buffy's room, you can see over the top of the set. The studio wall is clearly visible, as is the lighting instrument that is supplying the "sunlight" streaming in through the set's window.
At about 21:26, in a wide shot of Willow's and Tara's dorm room, a seated crew member can clearly be seen off to the left where the corner of the room should be. Additionally, part of the base of a piece of lighting equipment can be seen near the foot of the bed.
Just after Buffy finds Dawn reciting the resurrection spell, they head downstairs and start to argue. As the camera starts to move, the cameraman can be seen briefly in a mirror at the right side of the shot.