How did Juliet know "it worked"? When Juliet was near death, she was able to see a vision of the afterlife, wherein Oceanic 815 never crashed. She may have incorrectly assumed that they had been successful in preventing the Incident, resulting in Oceanic 815's safe landing in Los Angeles. However, she also said to Sawyer as she was dying, "We should get coffee sometime. We can go Dutch." Later, when she met him at the vending machine in the flash sideways, she said the exact same thing about going Dutch for coffee, followed by "It worked," referring to the trick she suggested for getting Sawyer's stuck candy bar out of the machine. So it is possible that those last thoughts, "It worked," that Miles detected from her grave, were actually her seeing her afterlife, and repeating what she said to Sawyer at the machine. ("LA X, Part 1") ("The End")

How was Charlotte Malkin able to communicate with Yemi? Similar to Juliet, when she was close to death via drowning Charlotte Malkin was able to see into the afterlife where she presumably spoke with Yemi who gave her a message for Eko. ("?") ("The End")

How is Desmond able to see visions of the flashsideways timeline? Since exposure to large amounts of electromagnetism can cause characters to see visions of their past and future, Widmore's experiment forced Desmond to see so far into his own future that he was looking at his own afterlife. ("Happily Ever After") ("The End")

How are the flashsideways characters able to see the events from the original timeline? Since the timelines were not actually separate, and the flashsideways timeline was the characters' afterlife, these visions occurred when characters were able to make some sort of connection with their previous lives, granting them awareness of the events they had previously lived out. ("Happily Ever After") ("Everybody Loves Hugo") ("The End")

