Back in July, the CW announced it would be crossing over its two DC Comics-based television series, with episode 8 of both Arrow S3 and The Flash S1 making up a two-hour special. Well, it looks like filming of the double-ep took place today, as Arrow star Stephen Amell shared a photo of him in his costume with Grant Gustin (the Flash). Granted, it's only a section of their costumes, but still. Are you looking forward to the crossover?