If there's one common filmmaking feature connecting all of the Star Wars movie trilogies, it's reshoots. Since 1977's A New Hope, directors on this franchise have never gotten it right the first time around, and all had to go back to correct little mistakes or entirely reshape plot points that didn't work in the initial cut.
That's not inherently a bad thing either, despite 'reshoots' becoming something of a dirty word in Hollywood over the past decade.
Yes, reshoots have led to big budget disasters like Justice League, but while they can indicate that a project has gone entirely off the rails, sometimes they can be the last piece of the puzzle that turns a good movie into a masterpiece.
However, even the smoothest scenes completed after principal photography can look a little awkward in the finished film. With actors having to come back months later sporting radically different looks, wardrobe departments losing key props or new dialogue having to be grafted onto already completed sequences, once you notice a reshoot inconsistency, it's hard to look at a film the same way ever again.
As a note, all of the following are reshoots that happened before the films hit theatres - George Lucas' special edition tinkering is its own beast entirely.