Are you thinking what I'm thinking?
The chemistry is there and since Arrow loves sharing exes lol...
That scene is a reflection of this season and how the producers don't care about attention to detail and logic anymore.
You guys want to know why Malcolm is not dead yet? Because the producers are infatuated with John Barrowman (SHH interview):
This infatuation is ruining the character and the show, Ra's should've killed him, but whatever. The episode was just ok, but Oliver needing to save the cops to know what he's doing was very contrived and artificial, he decided to be a hero in Season 2, to save people instead of just killing criminals from his father's list. He should know by now why he's the Arrow.
Ra's wanting someone like Oliver to be his successor is not believable. Oliver has shown his incompetence by how poorly he handled the Malcolm situation, besides, Nyssa shares Ra's philosophy, she's a better fit than Oliver. Hopefully, they will not ruin Ra's Al Ghul too, but is not looking very good at the moment.
For the ones saying how much better The Flash is, don't worry, they will ruin that show too. Like Arrow, they also use forced love triangles and we already have Barry and Iris cheating on Linda and Eddie, completely unnecessary and awful for the characters. The Reverse Flash plot is saving the show, but once he's gone, you know is not going to be as good.