'Arrow' season 5 news: Flashpoint storyline affects Diggle most; Echo Kellum previews Mister Terrific storyline

Both "The Flash" and "Arrow" returned with new seasons this week. But while the Flashpoint arc originated in Barry Allen's (Grant Gustin) world, it will have consequences over at Oliver Queen's (Stephen Amell) Star City as well.

"Arrow" executive producer Marc Guggenheim spoke to Entertainment Weekly prior to Wednesday's season 5 premiere and revealed that Flashpoint will be felt by Oliver and his crew during the current season.

"It'll affect Diggle's character the most, and that's all I really want to say in terms of spoiling how that happens," he dished.

According to the "Arrow" boss, Diggle (David Ramsey), who was revealed to be in Chechnya, is searching for the moral compass that he felt he lost in the season 4 finale. But soon enough, he will learn that Chechnya isn't exactly the right place for this exercise. Things will happen that will force him to return to Star City, where, as Guggenheim said, Diggle just won't be the same.

"He's not going to be able to live his life the way he had been living it before," the EP revealed. "Things are going to get very, very complicated for him, for reasons I don't want to spoil, but it leads to a very Dig-and-Oliver-centric episode in 504," he added.

Meanwhile, "Arrow" cast member Echo Kellum, who plays Curtis Holt, has teased the upcoming Mister Terrific storyline for his character. "Arrow" fans have long been waiting for the superhero, Curtis' alter ego, to emerge, and it now seems like they will soon get their wish.

"I think that we are definitely going to get into that Terrific aspect of his alter ego and that's going to be a lot of fun to watch," Kellum told Entertainment Tonight. He also said that it will be fun to see Curtis, who is the least experienced of the new Arrow crew, learn from Oliver and slowly progress into a superhero.

"Arrow" season 5 airs Wednesdays at 8 p.m. EDT on The CW.