When Buffy knocks at the French doors to Willow's bedroom, Willow opens the half to Buffy's right (Willow's left). They talk, then as Buffy starts to enter we see her (from behind) pull open the door on her left (the half Willow did not open) using her left hand. But when the view cuts to the reverse angle, that door is suddenly closed again and Buffy is facing the opposite way, pulling *closed* the door to her *right* (the one Willow opened originally) using her *right* hand.
(at around 31 mins) As Angel walks in front of the fireplace, on the left-hand side of the screen we can see what appears to be the red light, and faint outline of a camera.
When the detective is interviewing a witness he asks around what time she heard Finch scream. He never actually screamed.