First off…. If you haven’t watched episode 3 of season 5 DO NOT READ!!
We saw when Faraday talked to Desmond in the hatch in the first episode of the season that Desmond wakes up from a dream with a new memory.
In THE SHAPE OF THINGS TO COME in season 4 Widmore tells Ben he kept a bottle of macutcheon when the NIGHTMARES began.
Well tonight we learned Widmore is on the island when Juliet, Sawyer , and Locke and company travel back.
Remember Widmore has to kill his friend among other things concerning Juliet Sawyer and Locke.
Anyways…. These are the nightmares!