Never Kill A Boy On The First Date - S1-E5
Visible crew/equipment: When Buffy and Giles are in the cemetery, right before Buffy bails to go meet Owen, you can blatantly see a number rectangular studio/set lights reflected in Giles' glasses coming from various angles. (There wouldn't be dramatically-angled lights like that in a cemetery, let alone after dark).
Chosen answer: Angel is saying that he is still jealous and Buffy recognizes that this is his way of saying he wishes that they could be together. That is why they both smile.