In Broken Dolls, Oliver gives Roy a small red arrow to use as a signal to contact him. In the previous episode (Identity), Roy already has the arrow, as Quentin questions him about it after the car accident.
Correction: The small red arrow that Oliver gives to Roy is the same one Roy threw at him at the start of the scene.
When officer Lance buys a hot dog, it is large and covered in relish and mustard but, when he gets to his car and receives a police call, it looks like he's carrying an empty bun with no relish or mustard.
Shado lifts the arm of a skeleton and the whole hand comes up. Once a body's tissue decays, the bones are no longer connected and separate if moved.
When looking over the skeleton on the island, Shado claims that she was pre-med in college in China. Chinese colleges do not offer "pre-med". A medical degree in China is a four year bachelors degree.
At 13:00 when Quentin Lance is talking to Tony Daniel, Oliver's shadow is seen on the wall behind Lance, moving from left to right, suggesting the person casting the shadow is moving away from the office. As Tony Daniel turns around 180° to look behind him, the body double casting the shadow is briefly visible through the window, but Daniel is now facing Oliver. If Oliver had crept into the office from Tony Daniel's right side as implied, the shadow would have moved from right to left.