I'm doing a subject at uni and the information that the lecturer is giving on a certain aspect is incorrect. This certain aspect is something that I know quite a bit about as I've been researching it for decades.

Would you let your lecturer know they have incorrect information?

I'd not do it in an open forum situation but via other means (probably email as I can cite sources correctly in that).
I have corrected my lecturers many times in the past, most of them appreciate someone pointing out the mistake so they can fix it, or debate the issue with you. They also tend to like to use oppertunities like these as learning points for the entire class in my experience.