I'll toss in a couple more. These are things JWs teach which cannot possibly be true. Whether or not they are "biblical" is a matter of debate.
1. JWs teach that the "Adam" and "Eve" of Gen. 2, 3 and 4 were the first human beings to ever walk this earth. And they tell us God created Adam in the year 4026 BCE. However, modern science tells us that this cannot possibly be true. Paleontologists, anthropologists and archaeologists all assure us that mankind has lived on earth far longer than 6,028 years. Scientists tell us that people just like us have lived on earth for at least 100,000 years. For instance, anthropologists assure us that North America has been continually inhabited for 15,000 years and Australia for 35,000 years. Several different very reliable methods of dating ancient materials and human habitations have been used to establish these facts. The JW teaching that people have lived on earth for only 6,028 years is absolutely ridiculous. But it gets worse.
2. JWs actually say that the surface of our earth have been continually inhabited for only 4,372 years. For they teach that a global flood completely destroyed our planet's surface, along with all evidence of any prior human civilization, in 2370 BC. Again, modern science tells us that this cannot possibly be true. That our earth has never been completely covered with water, since land masses first arose from its primordial global sea some four billion years ago, has been firmly established by modern science in more ways than I can possibly here begin to mention. For a discussion of this subject matter see the article "Problems with a Global Flood" at http://www.talkorigins.org/faqs/faq-noahs-ark.html These things being so, if the Bible's story of Noah's flood is a true story, it must have been a large local flood confined to Mesopotamia which destroyed the entire "land" of Noah, not the entire earth. "Earth" and "land" are the same word in Hebrew.