TYPO - Possibly a good thing for you
If you are certain that the ORIGINAL traffic citation has the incorrect date, then it would be in your best interest to take it to court. Forget about calling it a typo though, but rather find proof (hard evidence) that you were somewhere else at the time of the citation and, therefore, cannot be convicted.
I would lead off by asking the officer if the information on the citation is correct - DO NOT ASK IF HE REMEMBERS YOU. If he says "Yes" (which he will unless he wants to admit he's an idiot), then you have no more questions for him. All you need to do next is to submit proof (a time and date stamped receipt at a gas station / grocery store / etc., your time clock at work, etc.) that you were in another place at the time of the citation.
Even though you signed the ticket, since the officer agreed on the stand that the information on the ticket was correct - now every other detail, including the speed you were travelling, is now questionable, at best.
Make sure that you do not agree to "Preponderance of Evidence" as the standard of proof (the prosecutor will probably ask for this at the beggining), but submit for "Beyond a reasonable doubt". If that is denied, agree to using "Clear and Convincing Evidence" as the standard of proof.
Good Luck!