When Chiron and his mother are in their house and she asks him for money, his backpack is placed at his front, strapped over both shoulders. However, in several shots where he is seen from the back, there is no strap over his left shoulder. At one point he switches the backpack from his front to his back, but right after that, when his mother starts struggling with him, the backpack is at his front again.
Just before Kevin and Little wrestle in the grass, Kevin's gold chain goes from under his shirt, to over, to under again.
When Chiron is eating the meal Kevin prepared for him and finishes his first glass of wine, he puts the glass to the right of his plate, but in subsequent shots the glass is in front of his plate.
When young Chiron eats as a guest he is seen holding his fork differently than the adult Chiron in the diner at the end of the movie.
When Chiron dreams about Kevin after their phone call, they have not seen each other since high school and yet Kevin is portrayed as an adult. Chiron would not know what adult Kevin looks like. Chiron looks at his phone for some time after the call ends, presumably to find a picture of Kevin somewhere to find out what he looks like now.
When Terrel sits down with Kevin in the cafeteria: The background murmur of voices ("walla") is repeated. Most distinctly a few lines at the start of the scene being replayed a few minutes later.