After Jiro tells Nahoko that he's finished designing his plane, he falls asleep. Nahoko removes his glasses and places them on the floor behind their heads. In the next shot, from behind their heads, there are no glasses on the floor.
After the heavy rainstorm, Jiro folds the umbrella that he and Nahoko walked under, but the umbrella shows no sign of being wet once the sun shines and Nahoko's father appears.
The representation of a tuberculosis disease is already highly wrong from a medical point of view. (Topic infection and course of the disease).
When Mr Kurokawa tells Jiro that the secret police visited he calls them 'the thought-crime boys'. The term thought-crime wasn't coined until 1949 when George Orwell published 1984.