Okay, so Felicity studies the shaft of the arrow and apparently locates a patent number. So she can tell the shaft is patented by "Sagittarius", (which she helpfully explains is Latin for "the archer"), and that this particular arrow was part of a shipment of 200 units. So it had a patent number and a unique serial number? At this point, I'm wondering why the police needed Oliver or Oliver needed Felicity. Felicity writes down the address of Sagittarius: 10245 Wharf. Oh, I know where that is! That's the abandoned warehouse on the same street as Melonshakers! Oliver tells her she's remarkable. And also Merry Christmas, but she turns out to be Jewish. So he tries "Happy Hanukkah." He should consider doing some research on this woman, since he's relying more and more on her.
Laurel and her father are watching the local news, of course. The commissioner asks everyone to report anything suspicious to the tip-line. And also there's a reward for tracking down the hood. Finally. Laurel knows these killings weren't the original hood, even though the last time she came in contact with him, she was alarmed that he was clearly a killer. There's a knock on the door, which she expects to be her friend Joanna with some files. But it's Tommy, who wisely goes straight to Quentin to say, "Merry Christmas, sir." Laurel's mad that Tommy came over because she wanted to spend the holidays with her father. Tommy says it's because the holidays are a tough time without Sara. Anyway, the Queens are having a last-minute Christmas party, and he'd like her to be his plus-one. And he found something in some old photographs, which he gives to her as a present. He leaves and Laurel's father complains about her being friends with that guy. He hates Merlyns and Queens because they treat people badly. The present turns out to be a picture of Laurel, Sara, and Quentin Lance. We really haven't learned much about Sara Lance, except that she's the sort of person who'd sleep with her sister's boyfriend.