According to Arrow executive producer Marc Guggenheim, two characters from the Flash pilot will appear on Arrow later this season.

Arrow higher ups have been keeping the nineteenth episode of this season under wraps, but now we’ve learned a bit more about it.

According to Guggenheim, the episode, titled “The Man Under the Hood,” will be written by the team behind The Flash: Geoff Johns, Greg Berlanti and Andrew Kreisberg.

The episode will also feature Danielle Panabaker (bioengineering expert Caitlin) and Carlos Valdes (mechanical engineering genius Cisco), two regular members of the Flash cast, in what Guggenheim describes as “an important appearance.”

Panabaker and Valdes filmed their Arrow appearances at the same time as the Flash pilot, though the concurrent production schedules weren’t the reason behind the crossover.

“In fact,” Guggenheim explains, “that was an added producing/logistical complication. It’s just so much fun to see these characters before you — it’s like previewing Boba Fett in the holiday special.”

Their appearances “really came about because obviously Barry is in a coma at the end of episode nine [of Arrow],” Guggenheim explains.

“That pretty much made it impossible for Barry to appear in episode 19, 20 — pick an episode of Arrow — because he’s got to stay in a coma until October of next year.”

He adds, “[T]he idea of bringing in those characters really, really appealed to us because it allowed us to honor our original intention that we had at the beginning of the year, which was to do something Flash-related around episode 19 or 20 without, of course, having comatose Barry and basically paying Grant Gustin a lot of money to sit around with his eyes closed unconscious the whole episode.”

The problem with that idea? “It’s really boring.”

The appearance of Flash characters “allows us to further flush out The Flash universe in Arrow,” Guggenheim adds. “We get to see their dynamic.”

Are you looking forward to seeing ‘Flash’ characters in ‘Arrow’?