A Night at the Bones Museum - S5-E5
Factual error: Hodgins makes a remark about the mummy wrappings being for an important person because it is a diamond weave pattern. However, the diamond weave pattern didn't come into effect until the Greco-Roman period that began at 332 B.C. It certainly wouldn't be found in an 18th dynasty mummy, no matter how important he was.
A Night at the Bones Museum - S5-E5
Factual error: Hodgins says that natron was a naturally drying agent, which was used in the second century B.C. This is both wrong and right. While it is true that natron was used for mummification, it was used for thousands of years in Egyptian culture, not just the second century B.C.
A Night at the Bones Museum - S5-E5
Continuity mistake: The mummy is in direct sunlight with no shadows on him when Cam first walks up to examine him. When Bones and Booth walk up to him, a few seconds later, the right side of his face is in the shadows. (00:04:00)
Answer: Since the palatine bone is a bone that helps form the mouth it has a lot to do with speaking. The shape of it differs a lot depending on your ethnic background. I would guess that they, in the show, meant that the person's bone tells that they were Japanese and that it was "made for the purpose of speaking Japanese." That's what I'd assume anyway. I've studied molecular biology though, so I'm not an expert on bones.