Audio problem: When Gatsby and Nick are in his car driving to meet Wolfshime, in wide shots you can see that what Leonardo DiCaprio is saying does not match his mouth's movements.
Audio problem: After the barber shop scene, Jordan tells Nick about the tea date. While she talks, there's a side angle where her lips are totally out of sync with the audio.
Chosen answer: This has been answered before. Gatsby grew up in a poor, mid-western family. He is a self-made millionaire (through illegal means) but pretends he comes from wealthy, upper-class society. He has adopted a fake posh accent to help support the illusion of his bogus background. It is how he believes well-bred people speak.
raywest ★