Rave : 2004 : Continuity Cock-Ups, - Careless vs. Criminal 
There are a couple of careless things I've noticed recently in Marvel comics - the first being pretty minor. I've noticed that on the cover and splash pages of multi-part stories, often the numbers are screwed up. Check out Ultimate X- Men #45, which claims on the cover to be Part 5, but is actually Part 6 of the "New Mutants" story. Ultimate X-Men did the same thing with "Blockbuster". Daredevil did the same thing with the "King of Hell's Kitchen" on their splash pages a month or two back. Careless, but nothing more than a minor annoyance, to be sure.
The recent "Lizard's Tale" put Connors as being from Lousiana, rather than Florida as he should have been. There's also the continuity problem that Kurt never actually knew Peter's identity, plus the fact that his son was shown ten years ago as being around fifteen years old, but now seems to be younger again! Certainly they're a bit more serious than a mis-numbering, but in the grand scheme of things, that's really not too tragic. For the kind of "Criminal Cock-Up" I'm talking about, we have to head over to recent issues of Amazing Spider-Man. But before we start into the details, let me first just say that as a rule, I love JMS's work. I really do. Honestly!
Exhibit A: ASM #500. Spider-Man is in history-land, and he's re-living the scene where Gwen falls off the bridge. Well, is pushed rather than falls. Spidey thinks "I'll shoot straighter this time..."
Ooops! As we all know - Peter didn't miss Gwen. He snagged her ankle just fine. It was the sudden stop that killed her, whipping her neck and snapping it!
Exhibit B: Amazing Spider-Man #507. A flashback to the radioactivity exhibition where Peter got his powers. You see characters that are clearly intended to be Flash, Gwen and Harry.
Except that - if you've read Amazing Fantasy #15 you'll know that it wasn't actually a school trip that Peter was on, it was an after-school trip that he attended by himself. Flash had previously headed off in a car going to a dance with Liz, teasing Peter about going to a stupid science exhibition. Plus... Flash hadn't yet met Gwen or Harry (who actually went to a different high school). He made friends with them thirty issues later, in ASM #31!
So, obviously Flash changed his mind and decided to ditch Liz Allan, abandon the dance, and sneak to the evening science lecture, where he met Gwen and Harry, became instant friends, then forgot all about them until he met them at college. Well... except that when you turn the page of #507, you see Flash, Gwen and Harry among scenes of Puny Parker being picked on, before he gained his powers. Seems JMS believed that Gwen and Harry went to the same High School as Peter, Flash and Liz!
Sadly, it seems like Straczynski learned about the "Origin of Spider-Man" by watching the movie, instead of reading the comics. I find that really sad, to be honest. What's worse, none of the proofers picked up this major booboo.
Whenever writers go back to enhance/modify/re-invent the most integral story of one of the world's most recognised pop culture figures, you really would think that they would actually take the time to stop and read the story they're re-inventing. For goodness' sake, if anybody at Marvel is reading this... please throw a copy of "Essential Spider-Man #1" into Straczynski's in-tray!