Will the general population be aware of what is happening, or will their thoughts be in the past as well? (makes me think of the movie Momento)

If people forget what happened and are effected as well, maybe have a big war startup, Lord of the Rings style, and then have everything back to normal the next day.

The leader they found dead could be alive again and not know of being abducted/killed (because he hasn't been yet).

Things could be un-built.

Treaties unsigned.

People unborn.

Now, most of those were really general ideas, but you didn't give too many specifics. Maybe use my ideas as ways to give examples of things that will and won't work for the campaign.