I think it's just a glitch in the chapter numbering or Chapter 24 was just an author's note. There's no skip in the story line.
No, there's definitely a chapter missing. I'm reading it now and when I started chapter 25, it didn't make sense. It's referring to stuff that had just happened (between the end of chapter 23 and now) that I am supposed to know about but don't (ie: Edward tells Bella from this point forward, she's the girl in the video and I have no idea what video he's talking about and he's thinking about things that had just happened in their "scene" which obviously started in the missing chapter 24 and is continuing in chapter 25). That's how I noticed it. I wasn't even paying attention to the chapter numbers until then.