I get the production pressures, time constraints etc. I really do, what really annoys me is the thought that maybe they think the audience is too dumb to notice, or some such thought. I hope I'm wrong.
Let me add a little fuel. We were watching Robinson Crusoe on Mars (ok, crappy one I know but it's from my younger days) and when our leading man enters a cave he's never been in, as they pan right, there's a fire extinguisher that they probably thought was out of view. Hey, at least they're safe on the set? ;-)