Can we get even a stab at continuity? Please?

So I'd rented the movie 'Year One'. Because yes, I'm an idiot. A morbidly curious idiot. Anyhoo, I rented the movie, and saw one of the most egregiously bad examples of poor continuity editing that I've ever encountered.

Remember that scene - and if you haven't seen the film, I'm asking 'remember the trailer' - where Michael Cera, dressed as a guard, announces that he was never given a sword, and didn't know that's what the scabbards were even for?

Here's a screenshot from seconds before that line happens:

Can we get a close-up of that, Alex?

You know it, voice I pretend is there so I can give off an air of sexy, sexy, schizophrenia!

That's Michael Cera. There's his scabbard, and the sword that's in it.

How do you miss something this obvious? There's a joke about this like ten seconds later! Just how incompetent was every single element of this damn movie?

God damn it, I hated Year One.