Why can't mature red blood cells from a human undergo mitosis?

Eritrocytes also known as red blood cells do not have nuclei regarding to mammals.

If mother is Rh negative and father Rh positive could children have any problems?

Rh factor is something that describes presence of a specific protein on surface of eritrocytes. Most of people have that protein so they are Rh positive. Some of them don't, they are Rh negative. When a mother that is Rh negative, carries a fetus that is Rh positive she might develop antibodies against Rh factor. These antibodies are very likely to attack eritrocytes of fetus. Which might lead to hemolytic disease of the newbornor in another words eritrocytes of will be destroyed. A child It is most likely to happen with second born child rather than first because during the pregnancy of the first child mother still hasn't developed enough antibodies.

What might happen if you irritate your ear with too much water or if you have too much ear wax? Think outside the box!

Okay if you answered that it might break membrane tympani you were probably wrong. I said think outside of the box, not inside of it! So here is the OUTstanding answer: It could actually cause bradicardia or even dyspnea. 10th cranial nerve (vagus) is actually one to blame. He gives branches to ear as well as to the respiratory organs and heart. So if you irritate one segment of this nerve there is possibility it will affect other branches as well which might cause lower heart rate or problems with breathing.