Mook Horror Show: Those poor bastards on the Amazo get to experience first hand what the Mirakuru has done for Slade. The last two of a group who witness him plowing through them with his machete even try to flee. Key word "try".
Multitasked Conversation: Slade and Oliver snipe at each other and make veiled threats in front of Ollie's oblivious family.
The Mutiny: Oliver and Sara release the Amazo's prisoners in order to start a riot on the ship, which ends with Slade killing the Captain and taking over.
Mythology Gag: Curtis Swan and Joseph Cooper are mentioned as being 19th century artists. In real life, Curt Swan and Joe Cooper worked on comics for DC.
Oh, Crap: The expression of horror on Sara's face when she hears Slade's voice in the present.
The look on two mooks faces when they see a mask-wearing Slade cut through the others like a lawnmower and then set his eyes on them, before turning tail in a vain effort to flee.
Revenge Before Reason: One of the prisoners would rather kill Sara than take advantage of the fact that she just freed him.
Right Behind Me: Ivo accuses Oliver of letting Shado die just as Slade shows up.
Sinister Surveillance: It turns out Slade only wanted a tour of the Queen Mansion so that he could plant spy cameras throughout the whole building.
Training Montage: The opening has one of Island!Oliver preparing for the freighter takeover.