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: 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 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: 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.