This article describes differences between the two different timelines shown in Season 6, up until the moment that (in the original timeline) the plane broke apart. Note that this article describes circumstances in existence at or prior to the moment that, in the original timeline, the plane broke apart, even if the audience does not learn of the existence of those circumstances until later (such as the absence of the coffin, which is not revealed in the flash-sideways timeline until after the plane has landed).