Check out the preview for Season 4 Episode 9 of Arrow "Three Ghosts," which sees Grant Gustin back again as Barry Allen aka The Flash.
Tonight's episode saw the debut of Gustin as Barry Allen, which I thought went off really well. In addition to Barry Allen, the episode also featured Easter Eggs related to the Blue Beetle with Kord Industries and Star Labs got a mention. Allen also remarked about wearing a black costume instead of green (a nod to Batman). We also saw lightning flash when Allen was checking over Felicity's chemicals hinting at what's to come. Speaking of what's to come, the first appearance of Grant Gustin had him holding magazine on top of his head to protector himself from the rain which mentioned a particle accelerator.
Next week's episode marks the mid-season finale with Arrow returning January 15, 2014.
"Three Ghosts" Synopsis:
After a battle with Cyrus Gold, Oliver is poisoned and left for dead, and Felicity gives him an antidote that causes hallucinations of his past. Meanwhile, Brother Blood captures Roy, Barry continues assisting Felicity, and Lance loses someone when he tries to run surveillance on Cyrus.