Well, I feel like a complete idiot now. I was going to have my main characters visit a particular museum and wrote up the intro to the trip. I went online to find pictures of the interior of the museum and came across a small tidbit of information. The museum opened in 2011. My book takes place in 2000. <sigh> Thankfully, it was only a short paragraph that had to be deleted, but the rest of the lead up to a visit to the local castle had to be rewritten.
Ideally? I get a chance to go to Bavaria before the last book is finished.