Time travel is a concept that's been teased since day one of The CW's [The Flash](series:1068303) and according to the series' executive producer Greg Berlanti, expect for the concept to come up in a big way during the show's winter episodes. In an interview with TV Line, Berlanti stated that the freshman drama plans to "directly" deal with time travel during its winter run.
"We, obviously, hint at it from the pilot episode," Berlanti told TV Line. "That is a big -- 'theme' is the wrong word for it -- but that is a big part of the DNA of who The Flash was, so we do deal with that."
As alluded to by Berlanti, time travel has long been a significant part of The Flash's comic book history -- including the famous time-traveling "cosmic treadmill, introduced back in 1961, and multiple characters (such as Impulse and even Iris West) hailing from alternate timelines.
It's likely that whatever time travel concept comes during the winter will have something to do with Harrison Wells (Tom Cavanagh), who has been involved in many of the series' teases of a possible future. It's possible that whatever plot point comes in the winter may have been intended to ramp up for the original season finale as "The Flash" did not get a full season until October. Indeed, in the TV Line interview, Berlanti said "The Flash" team had "just started talking" about a possible "[Arrow](series:720988)" crossover for the back half of the season. Either way, the winter will undoubtedly bring big episodes for "The Flash."