Morgan Freeman and Todd Brun in “Unfinished Business”

  But there is one paradox that time-travel may create.  When time-travelling Todd turns over those time machine plans to his ancestor, that ancestor could then pass down those plans back to time-travelling Todd, who uses the plans to build the time machine.  Neither of them actually created the plans.

  The question is, where did the plans come from?  The plans seemingly appeared out of nowhere.