I must admit I have pet peeves about things I read (and watch). Here are a few that come to mind:
1) If I can take 30 seconds and fact check it on Google, or Yahoo, or whatever search engine, and find out all I need to know about it, the author should have done that, too.
2) If you are setting your story in the real world, I expect things to happen as in the real world--ie. the laws of physics still apply. If you are setting your world in a made up place, you need to be sure to create what your laws are and stick with them.
3) Not doing enough research for specific things in your story.For example, if you are setting it in a country you've never been to, you still need to research enough so those of us who have been there, or live there, have no idea you've never been there.
What are some of your pet peeves?