Should I tell the woman seated next to me that there was no need for her to bring two basketballs to an NBA game?
That's a weird thing to point out. Do you think she maybe just made an honest mistake?
No, the NBA game is played with five balls so she obviously must've noticed it.
There is no need to point anything out to this woman. It is bad manners to bring attention to someone's ignorance.
Why are you defending this woman? Do you know her?
No but it is easy to make a mistake when you don't know much about the topic or subject. However it is rude to point out an easy mistake and make the person look foolish.