My grammar pet peeves

I think my greatest grammar pet peeve probably has to do with dialogue. For example if someone put: "Let's go to the park." He said, I would literally stare at it for a moment as if willing it to change before my eyes. I absolutely hate it when people forget to put a comma instead of a period when it comes to dialogue tags. It just drives me nuts.

The other few things are probably the difference between its and it's, there, their, and they're, and lastly, when people don't put an apostrophe with verb contractions (i.e. don't is spelled dont).