Source : Webster's Revised Unabridged Dictionary (1913)

Misdate \Mis*date"\, v. t. [imp. & p. p. {Misdated}; p. pr. &
   vb. n. {Misdating}.]
   To date erroneously. --Young.

Source : WordNet®

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