• Arrow is CW Network series developed by writer/producers Greg Berlanti, Marc Guggenheim, and Andrew Kreisberg.

Arrow is CW Network series developed by writer/producers Greg Berlanti, Marc Guggenheim, and Andrew Kreisberg. (Photo : Facebook/Arrow)

"Arrow" season 4 first episode is full of secrets and Batman and Green Lantern is set to appear in the show.

"Arrow" cast members Stephen Amell, John Barrowman, Katie Cassidy and Mattew Nable were in attendance during the show's panel at the DragonCon 2015 event. The cast members had a wonderful time answering questions to the fans during the event and they explained several things regarding what is going to happen to Oliver Queen and the rest of the Star City heroes in season 4.

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Amell has teased fans of a secret element that will appear in the season 4 premiere of "Arrow" and stated that it is something that the show has never done before, Comic Book reported.

No one knows for sure what kind of element will appear in the first episode, but there have been hints and clues regarding other DC characters appearing in the show. Executive Producer Gregg Berlanti has teased a possible appearance of Hal Jordon/Green Lantern due the Coast City promo. Amell also stated that he wants Oliver to meet Bruce Wayne/Batman, but proved "too difficult" to place him somewhere within the show and it will be DC comic's decision if they allow the Dark Knight to appear in season 4.

He added that to truly understand the story of "Arrow's" season 4, they must first see what the premiere episode is all about, which will lead to clues that would leave a huge impact within the show. It is an interesting method and people will pique interest in it once they found out what that secret element is all about.

Amell also teased the possibility that the current UFC Women's Bantaweight Champion Ronda Rousey could guest star in the show as a fan pointed out the she "shipped Olicity",Realty Today reported. The "Arrow" star jokingly replied that Rousey could replace him anytime during the show and she can practically do whatever she wants.

The story of "Arrow" season 4 will have Oliver Queen (Amell) resume his vigilante identity and return to Star City to fight a new threat, Damien Darhk (Neil McDonough). Oliver will be reunited with Team Arrow consisting of Felicity Smoak (Emily Bett Rickards), John Diggle (David Ramsey), Thea Queen/Speedy (Willa Holland) and Laurel Lance/ Black Canary (Cassidy).

Season 4 will also feature old faces such as Malcolm Merlyn (Barrowman) and Nyssa Al' Gul (Katrina Law). New characters will be introduced in the series like Michael Holt/Mister Terrific (Echo Kellum), Anarky (Alexander Calvert) and John Constantine (Matt Ryan), as well as, the return of Sarah Lance (Caity Lotz) after she was killed during the events of season 3.

"Arrow" season 4 will premiere on Oct. 7 on the CW Network.