If the ticket incorrectly states the direction I was travelling, is that a fatal error?

Nope.

It might help you at trial but not as far as the "fatal error procedure" goes.

only if you keep your mouth shut, take the matter to trial, lead the officer in cross-examination to firmly state that you were driving on that direction of the highway. Then use his notes showing prior locations he's been, or your witnesses or anything else that you have to challenge the reliability of his testimony.

If your successful the officer's credibility will be shot, he will look like a loser in front the court, and you can then move to make your case saying that there is no reliable evidence that the prosecutor has to even prove this offence, you elect not to testify and you are asking for the charge to be dismissed on the basis of insufficient evidence.