how we know Locke's past is phony

Our clue is that Richard Alpert appears to be the same age in all the
flashbacks.  So he's our timer, our "constant".  It means the scenes
took place fairly recently, which means they were acting out a phony
past for Locke using different actors.

Another possible clue is the disagreement between the ear, which said
the music on the record was Buddy Holly's version of "Every Day", and
the closed caption, which said it was Don Mclean's.  That could also
be Damon's shout-out to the feud between Mclean and Andy Breckman.

Robert