Lost (season 6)
The sixth season followed two timelines, each an outcome of the explosion of a hydrogen bomb in the previous season finale. In the first timeline (referred to as "flash sideways"), Oceanic Flight 815 never crashes but lands with all leaving the airplane at Los Angeles LAX airport. In the second timeline, the remaining survivors return to the present day (on the Island) and must deal with the demise of Jacob, whose death has been caused by the mysterious Man in Black, the Smoke Monster. According to show producer Damon Lindelof, the term "flash-sideways" was deliberately used instead of "alternate reality" because it might then imply "that one of them isn't real, or one of them is real and the other is the alternate to being real."