I think finding little goofs can be fun ... and certainly not malicious. It's just like spotting errors in movies and tv shows - it gives you somethin' else to look at after you've inevitably finished the product.
But the only goof I could really find, that hit me, was early in the book when Jake goes back to Derry the first time and he says Frank Dunning took his kids to the Maine (in Orono) football game on the 4th of October. Except Maine played Vermont on that day ... in Burlington, roughly six hours from the fictional Derry.
Another mistake I found:
1. Jake noticed that Marina Oswald is pregnant and says that Al failed to mention this in his notes, and he is totally shocked.
2. Later we see that Al DID mention it in his notes, he mentions the 2nd baby being born.
Am I right about this?
Of course we all give SK a break! No one is perfect. I can imagine that if he's on a roll writing he doesn't necessarily stop and check every little thing. I certainly don't fault him for any of them. The one error that I caught made me smile. It occurred when George/Jake was coming into Texas. He noticed a "Don't Mess With Texas" sign. I've lived in Texas for over 40 years - we started that campaign in the mid-eighties.