According to Kryptonsite, beyond the previously announced appearance of Michael Shanks as Carter Hall (Hawkman) and Michael Hogan as Slade Wilson (Deathstroke), the episode "Icarus" will mark the highly-anticipated return of Stargate Universe's Alaina Huffman in the role of Dinah Lance, the Black Canary.
There is no air date for "Icarus" at this point.
For additional news and rumors about the episode, head over to Kryptonsite by following the link.