They gave us like an extra 1/2 beat on the off brand Russian vodka bottle she poured Ollie's drink from in the 2nd to last scene. I think if they had lingered on it for a FULL beat I'd have been sure it was a red herring, but because it was so quick, perhaps it was meant to be a clue for only those who happened to pick up on it. Because there's been nothing else pointing towards her involvement.
The DA, we assume, is Vigilante, so if it's going to someone known... the reporter makes some sense.
What/Why/How happend with Diggle?
What to make of the final scene revelation? Those? I have NO idea.
But agreed that it was an excellent mid-season finale!
One of Vigilante's Alter Ego's is Adrian Chase, so it's definitely him, but I suspect that he's also Prometheus. I could see the reporter being the daughter of another season 1 Arrow victim & having teamed up like Deathstroke did with Isabel Rochev in season 2.