Some of the issues and challenges that I encounter with finding information online is the multitude and accuracy of the different sites. There are too many sites which may not provided accurate information about certain entities and thus may lead to misinformation if research is not thoroughly done.
I certainly have some concerns about the platforms I use. The major one is Facebook. This is because by just accepting Facebook's user agreement, I am giving up the right to so much of my personal information and activity. This is the same for Instagram, which had been recently acquired by Facebook.
As a result of this, I find it very hard to initially trust some of the information I find online. I would usually use sites such as Google Scholar to acquire established educational content to use in my lessons. If not available there, I would do multiple comparisons across sites and textbooks, ensuring to crosscheck sources, definitions and timelines.