Other mistake: In the newscast at the beginning of the episode, they incorrectly broadcast Robert Queen's birth date as 1948. They use the correct date in Episode 2 when it is shown as 1958 on his gravestone. (00:02:25)
Other mistake: When Oliver returns from the docks, he puts his bow in the case and his hood down. This is footage which is run backwards from the scene where he suits up earlier on. The best point to see this is when he ultimately blinks: it's very unnatural.
Other mistake: Before the security guard is killed, he turns around and faces the direction of the camera. He is killed, and the camera backs up to reveal 6 men standing there. The security guard would have seen the men and he had time to react to them, but did nothing. (00:32:50)
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.
Suggested correction: When Diggle is walking away from Felicity, he is still talking to her but it looks like he is talking to Nyssa.
Stephen Edmonds 1
People have already tried to correct this mistake. It is valid. In the scenes prior, Nyssa says Oliver will do what it takes to kill her and Oliver says "tonight, Nyssa Al Ghul faces justice." Nyssa is there to bring the team the news that Oliver is going to try to kill her. Felicity says "Oliver wouldn't", meaning Oliver wouldn't try to kill Nyssa. Diggle says "I think what she's [she being Felicity] trying to say to say is that Oliver would never do anything to hurt you" [you being Nyssa whom Oliver is going to try to kill]. He is meant to say "Nyssa." Otherwise the entire line means Nyssa or Laurel are there to convince Felicity that Oliver would never do anything to hurt Felicity.
Bishop73