The Collaborative International Dictionary of English v.0.48:

Misdate \Mis*date"\, v. t. [imp. & p. p. Misdated; p. pr. &
   vb. n. Misdating.]
   1. To put a false or erroneous date on (a document). --Young.
      [1913 Webster]

   2. To assign an incorrect date to; as, the fall of Troy was
      misdated by medieval writers.
      [PJC]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "misdated":
   ahead of time, anachronistic, antedated, beforehand, behind time,
   behindhand, dated, early, foredated, late, metachronistic,
   mistimed, out of date, out of season, overdue, parachronistic,
   past due, postdated, prochronistic, tardy, unpunctual,
   unseasonable