Continuity mistake: When Obi-Wan says to General Grevious, "Not this time. And this time you won't escape", you can tell that it is a flipped shot because the moles on Obi-Wan's forehead are the opposite way round to how they are normally.
Revealing mistake: Computer generated characters that have light sabers (like Yoda) show a glow on them from their sabers when they are on. All "live action" Jedi do not.
Continuity mistake: In the fight scene between Obi-Wan and Grievous, look closely at the lightsabers in Grievous' right hands as he ignites them. The one on top is an Obi-Wan hilt(blue) and the bottom is an Anakin hilt(green). Throughout the fight, these two sabers alternate colors constantly between shots. When Grievous' hand is severed the second time, he drops the Obi-Wan(green) and retains the Anakin(blue).
Continuity mistake: When Anakin, Obi Wan and Palpatine are brought to General Grievous, as they are walking in just as Grievous says "ah yes" Anakin and Obi Wan turn to the left while Palpatine stands a little away from them. When Grievous says "General Kenobi, we've been waiting for you" Anakin and Obi Wan are turning left again.
Continuity mistake: The emperor sits up as he's using force lightning on Mace then a few seconds later he sits up again.
Continuity mistake: As Palpatine stands to face the Jedi, his right hand starts to turn around for his lightsaber. In the close up, his hand turns around again.
Continuity mistake: During the fight scene between Obi-Wan and Grievous, Grievous has the lower half of his left hand and upper half of his right hand severed during the saber duel. However, as he gets into his vehicle, the damage done to his right hand reverses itself and he is missing the lower half instead.
Chosen answer: Powerful force users seem to have some degree of control over their bodies even after death. In the later series, Luke's wife Mara Jade Skywalker only allows her body to disappear when her killer, and nephew Jacen Solo arrives at her funeral as a clue. Thus it appears that a powerful force user can simply choose if they wish their body to disappear.
Darius Angel