It will depend on what the lie was about. If the truth would have resulted in no license being issued, it would not be a legal marriage. If it is something such as the wrong age, but still old enough...
Assuming you are the testator, you would execute a subsequent will nullifying any prior will.Added: If you are challenging the will, you would have to raise the issue of the testator's mental...
In most states you need to be 18 or older, but in some states you can marry anytime you want with written permission from a parent or legal guardian from both sides.