Today, TV Guide revealed that Arrow and The Flash scribe Andrew Kreisberg has revealed that both Episode 8 on Arrow and The Flash will be a 2-Hour crossover event. With The Flash on Tuesday night and Arrow the next night on Wednesday:
“Episodes 8 of both shows, Arrow and Flash, are going to be a two-hour crossover event. [Also], in Episode 4, Felicity [Emily Bett Rickards] is going to come to The Flash.”
The Flash and Arrow Return to The CW this Fall