Ok, Detective Lance has seen that Sarah is BC. Sarah, who was lost at sea with Ollie. BC, who has been seen working with Arrow. Arrow and BC have both been seen in relation to Laurel, who dated Ollie. Arrow, who showed up to help against the assassins at the end. Who here didn't
expect Lance to whip around in that final scene and say "so, Ollie...".
I am beginning to think Lance has some Lane ancestry.