Referring to the previous comment about Serenity, actually, they didn't add any sounds in the space scenes - except when you were inside the craft, where the was air, and you could hear. Additionally, the music and editing actually tricks you into THINKING that you heard the explosion, but you actually didn't. It was really cool, actually.

Also, the movie Red Dawn followed rule number 2 in an early scene where an explosion in the background takes a few seconds to be heard. Of course, when I watched it, my friend actually thought it was a goof, until I explained that it was actually more accurate. It kinda gets to the heart of the matter on some of those mistakes... we're so used to them and reality sometimes feels so unnatural itself that it's almost jarring to see something realistic on these matters.