Two that come to mind:

People would say that’s an “old timey” car or something and I thought that was a brand name.

I thought the people who had really tall spiky mohawks had hair that just grew like that.

I remember believing this as well but specifically you had to kiss in a bed.

I would probably keep my nephew in my summer palace after murdering his dad for being too popular and then killing the rest of our family around him. Caligula turned out well, although to be fair I only read up to his first year as Emperor…