What causes people to remember events which did not take place?
There is some misinformation out there put forth by Brooks Agnew about "remembering the future".  This is the same guy who advocates a "hollow earth" theory.  It's not grounded in science, I'm afraid.

We predict and imagine the future.  Often our predictions aren't even conscious (reflexes, for instance, can be programmed in the lower brain; we're often not conscious of our reflexes until right after they've done their job).  But reflexes are a product of the past, either genetically, or through experience (depending on the reflex).

In fact, we generally consider it one of the arrows of time that humans remember the past and not the future; with Newtonian physics, deterministic physics implied events were completely invertible (reversible in time) while remaining valid.  This is one of the interesting features of classical physics.  There are now, many physically observable arrows of time, though: entropy, expansion of universe, quantum arrow (wave function collapse).

just a wiki article to get you started, 
http://en.wikipedia.org/wiki/Arrow_of_time