Yeah, they did replace Crimson Avenger with the more recent version, and Red Arrow subs in for Arsenal because they think Roy is dead. Is Vigilante also a replacement? Anyway, it'll all make sense.
Oliver did say, in a discussion with Black Canary in Infinite Frontier #0, that they were missing some memories. But clearly, they're starting to come back - and Ollie forgetting about his time travel is presumably why he didn't tell Emiko sooner.