Although I tend not to dwell on science errors in my SF programs/movies, even the most egregious ones, I do notice them and may comment on them. I try not to let it affect my enjoyment (hopefully) of the feature. But I do like lists like POPSCI’s Sloppiest Sci-Fi Movie Science Violations Of 2012, pointing out some of those really, really bad errors.
Not sure I agree on calling out the “travel back in time” thing as being impossible. After all, the Doctor does it just fine… 🙂