When playing Mah Jong with her three aunties, June cannot speak Chinese. However, when she arrives in China to meet her sisters, she is apparently fluent in Chinese.
In one scene, a daughter is shown cutting the flesh out of her arm to make a soup for her dying mother. In subsequent scenes her arms are completely smooth.
June's hair moves from in front of her shoulder to behind it several times just before Suyuan gives her the necklace.
When Ying Ying is talking to Lena in Harold's apartment, Ying Ying's multi-strand pearl necklace is twisted in some shots and untwisted in others.
In the second chess game that Waverley plays as a child with the boy the chess board and the positions of the pieces are clearly shown on the screen. The boy moves his queen. Waverley makes a move and the boy responds with a move in which he captures a pawn and he says "check". The only possible move that the boy could have made at this point which would have resulted in an utterance of any kind would have been "checkmate" - Black queen supported by black bishop takes white pawn, Mate. After this Waverley makes another move which would have been impossible under the rules of the game because the game would have been over on black's last move.
When June is playing in the piano recital, she says, in the voice-over, that she was playing Mozart. But the piece is the Dvorak Humoresque.
In the first scene where young Ying Ying met her future husband, the guy opened a watermelon which was totally seedless. The scene should be in later 1930s or early 1940s, based on the context. Very unlikely there was any seedless watermelons available in China at the time. Japanese scientists started seedless research in lab in 1938. It won't be widely available even in Japan market till after WWII.
When Lindo is at the beauty parlor, her daughter tells the hairstylist to color and perm Lindo's hair. Most stylists will agree that these two procedures should never be done during the same visit.
Thunder and lightning can't occur simultaneously unless you are extremely close to the strike.
On the road to Chungking, Suyuan leaves a letter with her daughters that is written in the Western layout: left-to-right, top-to-bottom. During World War II, the traditional Chinese layout would've been used.
June receives a letter from her half-sisters that is written in traditional Chinese layout: top-to-bottom, right-to-left. In the 1980s, a letter from mainland China would have been written using the Western writing layout.
When young Ying Ying's husband brings home one of his girlfriends, Ying Ying breaks a plate, sounding as if she's smashing it on hard floor. Yet the floor is covered with carpet.
During a break in the Mah Jong game, Jun plays three notes on the piano. The notes go down the scale but her fingers move to the right.
When Jun is at the piano for the recital, her fingers do not come down in time with the start of the music cue.