I will say she was mistaken because in the case of Dale Earnhart, she admitted she was wrong, and future editions of her book were corrected. The woman has written millions of words. She uses more facts than any other pundit I've ever read, and she is rarely wrong. But when she is, she admits it.
I'll give some more examples of mistakes she's made with facts and the reaction to them:
In one of her books she mistook someones grandfather for their father. As soon as this mistake was noticed, the knives came out and Ann was villified for it. Al Franken wrote, in one of his books, about this error and called it a lie by saying that the man was not the subjects father without ever once mentioning the fact that he was the subjects grandfather. Ann's confusing a mans grandfather with his father was a mistake. Calling her a liar without ever mentioning that the fact that she simply confused the relationship was a deliberate, and nasty, attempt to smear her. She admitted that mistake and corrected it.
Speaking of Franken, Ann once said that they had met socially and were "friendly". Well, Franken took great issue with that, and again called her a liar. Ann corrected that, too. She admitted that she did not mean to imply they were friends, just that they had met socially and were cordial to each other in social settings. I believe she said she should have used the term "civil" instead of friendly. But, seriously, how ******* petty can you get?
Ann was accused of lying by calling the end notes in her books "foot notes". Again, she admitted she was guilty of this terrible lie. She did refer to end notes as foot notes. And so do a hell of a lot of other people.
Considering the vast amount that Coulter has written, and the copious facts she uses to back up her opinions, she has made very few mistakes, has admitted and corrected every one, and none of them could possibly be considered a lie. Except by those who hate her opinions. And when calling her a liar doesn't work, they go after her looks.