DC seems to be becoming more and more serious about its different Universes interacting. And it's not just happening in the big screen, as it is also spilling over to the small screen. In fact, latest rumors point toward the meeting of the Green Arrow and the Green Lantern.

The Green Lantern's existence had been dropped here and there in season three of "Arrow" and season one of "The Flash." This caused some fans to speculate that Hal Jordan might be making an appearance soon.

But aside from the various references to Coast City and the mention of Ferris Air (where Hal is employed), what really pushed fans into believing that the theory is true is the "Arrow" season three finale, which showed Oliver Queen (Stephen Amell) headed to Hal's hometown.

As if that's not enough, "Arrow" executive producer Marc Guggenheim recently posted a photo in Twitter for the show's season four. The production art showed a Coast City postcard, complete with the first half of Green Lantern's oath, "In brightest day, in blackest night..."

It is far from a confirmation of the Green Lantern's appearance, but that, coupled with some SDCC teases from Amell himself, have really gotten fans hyped for Hal's encounter with Oliver.

During this year's San Diego Comic-Con, Amell confirmed that season four will be going to Coast City (if at least for the flashbacks). Asked if he will meet new friends there, he simply answered, "He'll meet an old friend."

Obviously, The CW and DC Entertainment have chosen to keep mum about "Arrow" season four specifics, but with or without Green Lantern, the Green Arrow promises an intense new season with the introduction of Damian Darhk as his new villain and Matt Ryan's Constantine helping him out.

Fans can soon find out answers to their Green Lantern questions and see the new characters when season four premieres on Oct. 7.