The new windows and some existing ones that have been changed all show a bright red sky but a few seconds later other windows have the original bright white sky.
The strangest change is Darth Vader talking to the Emperor.
One close-up shot in the 2004 version is identical to the original. A few seconds later the shot is a mirror image including the background. A bit later, it is back to normal again.
It is all the more obvious because Vader moves one way in the original version and the other way in the 2004 version.
The splitscreen really emphasises these errors.