Revenge of the Sith
Even with today's best technology the mistakes still creep through:

Reusing Stock Renderings or Just Lazy?
Here Grevious pulls out a lightsaber from four characters, Obi-Wan, Anakin, Ki-Adi and Adi Gallia. Although it would have been nice to see some more unique lightsaber's in episode III, they were either too lazy to render new ones or they thought no one would notice. Common guys, these are Star Wars fans watching this movie.

Note the Colors:
Anakin: GREEN
Adi Gallia: BLUE

The First Cut:
Adi (The Green One) is the first to go!

Color Blind Are We?
Remember the Anakin saber when ignighted was GREEN and is now BLUE

Color Blindness...Again
Remember the Obi saber when ignighted was BLUE and is now GREEN and a moment later is cut from Grevious' hand

Saber Switcharoo!
The Adi Gallia lightsaber that was the first to get cut from Grevious' hand is now back and GREEN instead of BLUE

Saber Switcharoo II
Ok, now the Anakin saber in the upper hand is now the Obi Wan and Anakin's saber has leapt to the lower hand and is GREEN again

Back Again
Now the sabers are back to the previous cut

Pointy Sabers?!?
Ok, since when have the lightsaber's had a need to be pointy? In all other incarnations of the blade in other films has been rounded.

Sidious Fighting with Anakin's Lightsaber?
Now more than two seconds before Sidious leapt from his chair he was holding his own lightsaber. Now, shown in the following stills, shows Anakin's lightsaber in his hand. Why? The scene was re cut late in post production. Anakin was to have entered the room BEFORE Mace and the others showing up. Anakin is momentarily incapacitated and Sidious, having his own cut from his grip is left having to use Anakin's saber. As a consequence, Ani's saber is still visible in the sequence of shots.

Ian McDermott had his face digitally replaced on a stunt double for many sequences. As a result, some quick shots are less than convincing.

Saber Switcharoo...Here We Go Again
Shot One: Obi-Wan holding his own lightsaber while Anakin forces it down onto him

Shot Two: Obi-Wan now holding Anakin's lightsaber. I'm sure there's an explanation for this or the person in charge of continuity was on a break or something.

Inconsistent sound effects constantly riddled the movie. In countless cases, specific character lightsaber's have very specific ignition and extinguishing sounds. These were constantly being mixed around making it confusing at times. For some reason there are more inconsistencies in Revenge of the Sith than in any of the other movies.