Audio problem: Blanc and Lionel are talking about Andi on the ship headed to the island. "In one legal move, he cut her out completely", Lionel says, but the second half of the phrase his chin (as you can tell by his conspicuous beard) is not moving. (00:18:45)
Audio problem: When Lionel tells the others to lift the button at the center of the compass, you can notice that the music box is still playing, but the drum of the machine is still. (00:08:30)
Audio problem: Lionel learns that the whole Glass Onion runs on the dangerous power source. He tries to quit, but Miles puts a hand on his shoulder and says "Bro, you are not getting out." Edward Norton's lip movement does not match the sentence. (00:45:20)
Audio problem: Helen reminds Miles the line he used "To forever be remembered in the same breath as the Mona Lisa." The line is said in the span of a couple different angles; when she says the word "in the same", the camera is behind her, and you can see that her jaw is not moving. (02:09:15)
Audio problem: The second time we hear everyone reacting to Andi's death, the timing of the lines is different and Edward Norton says "God, Andi." (01:46:00)
