Here's a nice little detail:
Take the rusty sword, shove it in the iron maiden, then leave the room without killing the zombie you just skewered and...
Oh! I forgot to mention: This is what the auto-save screen looks like - as if it's footage being recorded through the security system. I thought that was really cool :D
OK so these "hang on a sec" messages seem to come up with some sort of consistency - they seem to be when there's something of interest nearby (even if you can't interact with it yet)?