Grant Gustin is feeling confident about “The Flash’s” fifth season, which begins in October. The actor, who plays Barry Allen/The Flash on the series, told reporters at Comic Con that he believes that this year could be the show’s best — starting with the premiere. Gustin says he thinks they can get there again. “I’ve been comparing it to our pilot,” Gustin told reporters at Comic Con. “I think it’s our best [season premiere] since our pilot.”