Factual error: When The Hood busts into the underground casino, the throws a guy through a glass table, and it breaks into large shards. He then proceeds to grab a handful of safety glass, so it's not the same glass anymore, and he throws it into the face of a guard, and it hurts him badly. Safety glass is designed precisely to prevent that. It is impossible for the pieces to get lodged in the guys face, no matter how hard The Hood throws them.
Continuity mistake: When Oliver drinks his tequila, the hand with which he holds the glass keeps changing.
Other mistake: When the Huntress is attacking the safehouse, she fires a shotgun blast at Green Arrow who's several feet away, hitting a door behind him and leaving a small hole, as would be made by a slug, rather than pellets (which would have spread out a lot over that distance). She then shoots the door lock right next to her, which gets riddled with small pellet holes.
Continuity mistake: Oliver chops off Malcolm's hand to end their duel. When Oliver hands the ring over to Nyssa you can see Malcolm lying in the background where he has been cut down with two hands intact, and the cut off hand nowhere in sight.
Blood Debts - S4-E10
Continuity mistake: When Conklin is whipping Oliver during an island flashback, the wounds from the whipping are visible, but after Oliver threatens to shoot himself unless Taiana remains unharmed he hands the gun to Reiter, and we get a good look at Oliver's back, wound-free.
Continuity mistake: Yao Fei takes the bow away from Oliver in one shot, then Oliver hands it to him in a following scene. (00:02:10)
Chosen answer: "C'mon Doll" by My Goodness.
Bishop73