Biblical inerrancy isn't one of the fundamental tenets of the Christian religion. One can be a believing Christian--who really does beleive Jesus is the Christ, the eternally begotten Son of the Father, the Logos, who suffered and died for our sake and who really did rise from the dead, sits at the right hand of the Father, and is coming again in glory to judge the quick and the dead--and still accept that some of the historical tidbits of the Old Testament might have been fudged or otherwise were less about strict historiography as they were about Israel's identification narrative as the covenant people of God.
I am inclined to believe that the Exodus, the single most important part of Israel's identity narrative, does have historical basis; but that it is still possible that it happened differently and perhaps quite less in such a grandiose way as described in the texts. This isn't a make or break part of my faith.
-CryptoLutheran