The Flash Season 2: 28 Easter Eggs & References You Might've Missed
22. Robert Queen
When over on Earth-2 with Harry Wells, a news report (on Channel 52, obvs) is discussing the reveal of the vigilante known as the Hood. While this means that he's still in the early days of his 'career' on that Earth, rather than being the Green Arrow we know, the bigger surprise is that it's not Oliver Queen. Instead, it's his father Robert who has taken on the mantle, in order to get revenge for his dead son.
This bears some resemblence to Flashpoint, which sees Thomas Wayne becoming Batman, and it turns out it may have been some early foreshadowing on the show's part.