If you wish to believe that there's a grain of truth in the exodus story, that's quite OK. I dont want to dissaude you, but if you're just discussing the matter then its probably important to know that most scholarship dismisses the Exodus as a foundation myth.
And if, again, as much scholarship will assert, that these texts were compiled (even if from earlier stories) during the exile in Babylon, and, (again, if) they were written by members of the elite, for the elite then it would not have been difficult for them to talk about real places located between Israel and Egypt. Many of these men would have travelled between Judah and Egyptian, and after the first group of Jews were exiled, some chose to escape to Egypt. So we have no need to believe that at any time the Israelites/Jews lived in isolation. They were very much a part of the Eastern Mediterraean culture, and knew of towns and roads and geographical features between Judah and Egypt.
This wikipedia entry is likely close to the truth as we know it:'
https://en.wikipedia.org/wiki/History_of_the_Jews_and_Judaism_in_the_Land_of_Israel
The various national groups of both the bronze and iron ages were interacting. Greek traders (as an example) went up and down the Mediterranean coast and Egyptian ships the other way. Then there were the Phoeniceans who traded all over the Med.sea and the Sea People, both on their own account and as mercenaries. All cited to demonstrate the extent of the interaction just at sea.
I cite that to argue that 'real' things and events woven into a myth doesn't make the myth true.
An editor working on national religious history during the exile, when they had nothing much to do except eat and drink and talk would've had little difficulty in knowing or finding out information that gave an impression of reality,
Somewhere I've posted on the Egyptian Empire and the inclusion of areas which the Israelites later claimed as their homeland - cant find it today. In the meantime you may like to check someone else's work:
http://www.jehovahs-witness.com/topic/141226/book-exodus-total-b