I'm a Ph.D. student in linguistics and a relatively new course instructor. My understanding of the material is not in doubt. But I'm doing a really poor job of catching small errors. Even when I check my lecture slides afterwards, I don't find them all. Almost every week, I'm having to email my students at least once telling them that diagram X was mislabeled or example Y was in the wrong place or I said something completely backwards. I don't want to end up overapologizing, but I feel like my teaching is unacceptably sloppy. I do put a lot of time and effort into considering/rehearsing how to teach things, and I compare my approaches to materials from several previous instructors of the same courses. This does not seem to have been enough.
I normally take pride in getting details right. Heck, I used to work as a proofreader and built up quite a stellar reputation! I know that teaching a course is a big job and that I have the instincts of a perfectionist. Nonetheless, I'm doing a much poorer job than usual when it comes to getting things right. If I were one of my own students, I think I'd be rolling my eyes at myself by now.
What sorts of strategies do others use in order to catch errors in their own teaching ahead of time? I'm very urgently wanting this to be less of a problem. There's no need for these little disruptions and I'm irritated with myself for confusing my students so much.