Fans of The CW's slate of DC superhero shows ("The Flash," "Arrow," "Supergirl," "DC's Legends of Tomorrow") recently learned that the Dominators (gene-manipulating aliens who have plagued the Legion of Super-Heroes and Justice League) will be the big bad villains for the "Arrowverse" crossover event. While it remains to be seen how the Dominators will be adapted from the comics to the small screen, there are new behind-the-scenes photos of the four-show crossover that give hints at S.T.A.R. Labs' involvement.RELATED: Arrow, Flash, Supergirl, Legends of Tomorrow CW Crossover Villains RevealedThe photos, shared on Twitter via YVRShoots, a paparazzi company specializing in photos from Vancouver-based television productions, reveal a sign for "S.T.A.R. Laboratories Aerospace Division."

S.T.A.R. Labs, as we know, is where Team Flash works to investigate meta-humans in Central City. Seeing a visual reference to S.T.A.R. Labs isn't of particular interest in and of itself, of course -- you'd be hard-pressed to watch an episode of "The Flash" and not see more than one scene inside the science facility. What is eye-opening is seeing a sign for the previously unmentioned Aerospace Division.

Could the presence of the Dominators push the DCTV heroes to venture out into space to hunt the villains for DCTV's first off-world adventure? Is this an example of the long-lasting repercussions Flashpoint will bring to the Arrowverse? Or is it heralding the first television mention of DC Comics cosmic police force, the Green Lantern Corps? No announcements have been made regarding the Corps appearing on The CW, but perhaps a Lantern or two will be name-dropped while discussing the Dominators.

Additional behind-the-scenes photos include Supergirl (Melissa Benoist) and The Flash standing shoulder-to-shoulder inside the S.T.A.R. Labs hangar, along with White Canary (Caity Lotz), Green Arrow (Stephen Amell), and Flash taking a selfie outside on the runway.

The four-way crossover is scheduled to air in December. "The Flash" returns to The CW on Oct. 4, followed by “Arrow” on Wednesday, Oct. 5, “Supergirl” on Monday, Oct. 10, and “DC’s Legends of Tomorrow” on Thursday, Oct. 13.

Starring Grant Gustin as the Scarlet Speedster, "The Flash" airs Tuesdays at 8 pm ET/PT on The CW. The series also stars Jesse L. Martin, Tom Cavanagh, Carlos Valdes, Candice Patton, Danielle Panabaker, Keiynan Lonsdale and more.

Starring Stephen Amell as the Emerald Archer, "Arrow" airs Wednesdays at 8 pm ET/PT on The CW. The series also stars Emily Bett Rickards, David Ramsey, John Barrowman, Willa Holland and more.

Starring Melissa Benoist as the Girl of Steel, "Supergirl" airs Mondays at 8 pm ET/PT on The CW. The series also stars David Harewood as Martian Manhunter, Mehcad Brooks as Jimmy Olsen, Chyler Leigh as Alex Danvers and Jeremy Jordan as Winn Schott and features appearances by Calista Flockhart's Cat Grant as well as Tyler Hoechlin's Superman.

Airing Thursdays at 8 pm ET/PT on The CW, "DC's Legends of Tomorrow" stars Arthur Darvill as Rip Hunter, Brandon Routh as the Atom, Victor Garber and Franz Drameh as Firestorm, Caity Lotz as White Canary, Maisie Richardson-Seller as Vixen, Dominic Purcell as Heatwave and Nick Zano as Citizen Steel.