Audio problem: After Anakin kills Count Dooku, Palpatine says, "Remember what you told me about your mother and the Sand People." In the next shot, his head is shown from behind, but if you watch closely, you can see that his jaw is moving as if he were talking, but nothing is heard. Use zoom for confirmation.
Audio problem: In the scene where Anakin turns to the dark side, Darth Sidious says, "You're fulfilling your destiny, Anakin." As he says this, his head is shown from behind and is in shadow, but the words don't match the motion of his jaw, and his profile shows that his mouth is moving after the words are heard.
Audio problem: When Obi-Wan speaks on R2-D2's radio, the sound editor cut a lot of frequencies, bass and middle, to make it sound like a radio. But when R2-D2 puts the radio in his shell, "magically" there is a lot of low middle in the voice. It does sound like Obi-Wan is talking from inside R2-D2, if it wasn't a radio, but in this case it is and shouldn't sound much at all, when the shell cuts the high frequencies. No low frequencies + No high frequencies = No frequencies.