I don't want to contribute to focusing this thread on Star Wars "errors" when it's actually about the Despecialized Edition, but regarding the stormtrooper hitting his head:

Putting aside for a moment the likeliness that the actor playing the stormtrooper wasn't scripted to do that and that this was captured in the take that ended up being used...... why is it necessary to view this as something that's wrong with the movie, and why is it necessary to view its removal as a "fix"? Is there something about the inherent nature of stormtroopers that makes a particular stormtrooper bumping into something an impossible event? Couldn't a stormtrooper making a mistake on screen be viewed as something that adds realism to the world of the movie? Anyway, that's my perspective on it. I think some people prefer to view it as an error instead of the approach I'm taking because pointing out things that are "wrong" with a movie makes a person feel clever.

A lot of details end up in movies that weren't planned but are still realistic and give the movie character. I think if a fan makes an edit of Star Wars focused on fixing errors in the movie, they should fix things like the shirt that changes color between shots, but leave the stormtrooper head-bang alone (I will refrain from mentioning a particular fan edit to keep this from being personal).