When there are scenes, where the author obviously doesn’t know what he is talking about.

I read a book, where they had lab mice and needed one pregnant. The hero of the book (a scientist) told his assistant, that he knows one of the mice was two weeks pregnant.

She goes crazy in awe how he, the absolute genius, was able to find that out, since there is no way to test that!

I have worked in labs with mice. First of all, a mouse is pregnant for three weeks. So at 2 weeks you don’t need a test anymore in most cases, since the mouse should look like a little balloon. At least the white ones tend to do that. Second thing, ultrasound works on mice too! We did it all the time for the embryo transfer!

And this author has the audacity to claim at the end of the book, that he himself is a scientist and is so much informed, so we as a reader could even learn the one or other thing.

I hated working with scientists for that exact reason. Many are friendly and really great, but some really think they are geniuses while acting stupid af.