I saw this last week and looked that one up too. Not only are the parallels bogus but the Egyptian book doesn't even tell stories about Horus. The parallels with he makes with Krishna and Mithra are also messed up. I don't think he is deliberately passing bad information, he just didn't care enough to do the research.
IMO he did a good job finding a wide sampling of the bizarre and idiotic in Christianity, Mormonism, Judaism, and Islam and mocking them. Some of his shots are fair, others are not. The movie works as entertainment but not as a logical sustained argument.