Can a judges decision in a divorce be overturned?

You can appeal the ruling, but to do so will have to be able to point to either some error of law (e.g. the court interpreted the law as pertaining to asset division, support, etc. incorrectly) or some extreme factual error (appeals courts only reverse trial courts on the fact when the "record" shows that essentially no one could have drawn the factual conclusions or findings that the trial court did; because the trial court listened to any testimony and they did not, appeals courts defer to them about factual evidence). Being late to court may not be enough of an error, since the courts are allowed to proceed with cases and make rulings in the absence of a party if that party misses the trial date/time: otherwise, people could endlessly delay litigation by not showing up and thereby putting the adjudication on hold.
In my experience, appeals work far less than half the time and can be expensive--several thousand dollars or more, between lawyer fees, filing fees, and the costs of gettng the "transcript" of the proceedings in trial court. While it's worth consulting with an attorney or three about the case, to see if you should appeal, do so with a sense of skepticism: any lawyer who overpromises (e.g. assures you it will work) is likely just trying to get your retainer. Listen skeptically to the attorneys, then decide whether to go ahead.
Note: there is usually a fairly short timeline to file an appeal, so if you want to explore this option, do it know.