Audio problem: After the buzz droids land on Obi-Wan's starfighter, Obi-Wan says, "I'm hit. Anakin?" As he says, "Anakin?" his head is turned to the side, but you can see that the last word doesn't quite fit his lips or the motion of his jaw. (00:05:10)
Audio problem: After Anakin is appointed to the Jedi Council, Ki-Adi-Mundi says, "What about the droid attack on the Wookies?", but the first two words don't match the movement of his lips. (Even though he's an alien, his lips always move like the lips of a human.). (00:36:20)
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. (00:14:20)
Audio problem: When Padme is trying to convince Anakin to turn from the dark side on Mustafar, Anakin says "And I'm doing it for you, to protect you." If you look closely, his mouth says "And I'm doing it because I love you, to protect you."
Audio problem: In the beginning of the scene in the Opera House, the audience is cheering and clapping, but in the two shots where the audience is shown, all of them are sitting still with their hands in their lap. (00:41:20)
Audio problem: When the young Jedi is killed and Bail Organa shouts "No." and climbs into his ship, shots can be heard but no lasers can be seen. (01:21:35)
Audio problem: In the scene where Ki-Adi-Mundi is killed on Mygeeto, he yells, "Come on", but the words don't match the movement of his lips. (He moves his mouth like the lips of a human, even though he's an alien.). (01:18:05)
Audio problem: After Palpatine reveals to Anakin that he's a Sith Lord, he says, "But you're not sure of their intentions, are you?" When he stops talking, his mouth is still moving. (01:02:25)
Audio problem: After Anakin tells Mace Windu that Palpatine is a Sith Lord, Anakin says, "I must go, Master," and Mace answers, "No," but his lips are saying something else. (01:05:45)
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. (01:12:20)
Audio problem: When Obi-Wan jumps down onto the floating platform in the lava river, the hum of his lightsaber is heard, even though the blade is turned off. (It's not Anakin's, as he's too far away at this point.) (01:51:45)
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. (00:09:40)
Answer: Darth Vader has a special chamber in which parts of the suit can be removed for comfort. When he is not in the chamber he must wear it at all times in order to survive.