Correcting someone is a delicate business. In a lot of situations, you don't want to make a fool of them, but you still want to point out they're wrong. Speaking with the How to do Everything podcast, former diplomat Angela Dickey suggests you ask them questions to lead them to the correct answer.
Photo by Tsahi Levent-Levi
The idea here is to call them out on their BS without directly calling them out. In this case, it's about asking them a few questions to make them think about what they said and figure out for themselves when they're wrong.
I think the best thing is to get the other person to try and think about whether or not they're correct... You could say something like, "Where did you hear that? That's really interesting."
She then follows it up by talking with the host about whether Michael J. Fox was in Star Wars or not, asking questions along the way to guide him to the right answer. Obviously there are plenty of people you can just call out when you need to do, but when you need to be a bit more graceful, this should help. Head over to How to do Everything for the full podcast and more tips.
The Diplomat and the Goatherd [How to do Everything]