Larsinger58,
If we don't use critical techniques (remember, "critical" here doesn't mean what "critical" means in the vernacular; a "critical" approach is where one uses reason and empirical evidence to understand a subject, often employing an academic methodology to do so), then the book of Exodus is filled with mistakes if we try to make it into a literal and chronological historical account.
One example is that according to the narrative of the fifth plague all of Egypt's livestock dies. Then when the plague of hail and fire rains down, the dead livestock get killed again. Did God kill the animals in one plague and then resurrect them just to get slaughtered in the next?
Using critical analysis allows us to compare this type of detail with other literature contemporary with Exodus. The genre of "epic" turned historical accounts into legendary "song," so to speak. In such a genre elements are embellished with imagination, humor, and larger-than-life possibilities. In this instance the critical method provides us with reliable data to see that the author of Exodus was purposefully writing the details like this, as it was common to use humorous elements to explain how daft a person was being. In this case the Egyptians had to be idiots to allow more than five plagues from God to come down upon them. But instead of using derogatory terms, and because legends allow room for it, "stubborn-headed stupidity" is illustrated in the detail that the Egyptians lost all their livestock ‘not once, but twice' at the hand of God!
And the writer of Exodus goes further by employing Biblical numerology and having the livestock "die" three times, at least the firstborn by means of the final plague of the first Passover. If the critical sciences are not correct, and one should go ahead and view it as history, then how on earth do you kill animals three times in succession like that? Instead of making fun of the opposing Egyptians, such a rejection of academic study leaves conflicting details like this to make the Exodus narrative itself look foolish.
There is historical evidence to suggest that one or more exodus runs of slaves occurred in Egypt. Further secular accounts regarding observed natural phenomenon that matches some of the miracles associated with Israel's exodus-like the Red Sea (or Reed Sea) parting-add unexpected witness to the weight of the historical basis for the book.
But there is no consensus that Exodus is either myth in the vernacular sense or even fits the pattern of ancient mythological genre (it isn't a story of origins like Genesis, for example). All that is agreed upon is that this is a legendary retelling of historical events, the exact details not preserved, to highlight the religious lesson learned by Israel as God freed them from slavery and led them to Sinai and the Promised Land. The examples you provide are not universally held. They are extreme views of but a few scholars.
That other details of the historical exodus did once exist but were not included in the inspired account is the testimony of the apostle Paul who gives the detail that two Egyptian priests were the thorn in his Moses' side, the ones who used their magical arts to try to explain to Pharaoh how certain wonders, like the Nile turning into blood, occurred. In fact, Paul gives us their names, Jannes and Jambres. The tradition from which this derived (and even inspired other narratives) comes from the same historical source that is at the basis of Exodus, and thus the New Testament itself is witness to this work not being literal history.-2 Timothy 3:8.
This is just some of the reasons why a fully academic approach of the text (which is what "critical" stands for) can be not only informative but useful in showing the validity of the books people refer to as Scripture.