Greedo's subtitles not appearing on-screen.
Some might think this a minor point, but the subtitles obscuring part of the image and focusing your attention on the written words distracted audiences from the less-than convincing alien suit that was only two steps beyond a zipper-head.
Whether you buy that or not, it's on the film print in '77, and it's never been on any home release that I know of. This contributes to an unauthentic feeling in that part of the film ... not to mention that folks with 16:9 screens often can't see the subtitles at all.
In the age of 16:9 screens and larger screens becoming commonplace, I think the convention of removing subtitles from the film image and re-entering them in a different, usually much larger, font in the black-bar area should abandoned.
.