Other mistake: At the beginning of the movie at the police station and the next morning at breakfast, it at least appears to be established that Grandma lives with Jim and his parents. After all, they had just moved from another city and Grandma was there early in the morning at breakfast time. However that's the last we see of her. She is never mentioned again nor is she there after Jim comes home from school or at anytime after the trouble starts. It would be unusual for someone to sleep through all that went on; but no one ever says anything about "being quite or we might wake Grandma up." After that scene at breakfast, she is forgotten.
Other mistake: In one scene a station wagon pulls up with a 300 to 400 pound dead deer draped over the hood. Later, as the shot changes, one of the hunters can be seen in the background easily carrying the obviously fake deer.
Other mistake: During Lady's first night home, there's a shot of the family's clock: the number seven is painted as a six.
Other mistake: While all the business signs in downtown Osaka are properly in Japanese, the local newspaper, The Osaka Times, is printed entirely in English.