The Collaborative International Dictionary of English v.0.48:

mistiming \mistiming\ n.
   The act or process of assigning something to a time when it
   could not have existed or occurred.

   Syn: anachronism, misdating.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

mistiming
    n 1: something located at a time when it could not have existed
         or occurred [syn: anachronism, mistiming, misdating]