Answer:
The account in Exodus is not the description of an escape. After a year of natural
calamities and catastrophes that demonstrated the powerlessness of each of their
deities, it began to dawn on even the dullest of the Egyptians that maybe all that
cheap labor was no longer worth the price. When they had finally had enough, Pharaoh
summoned Moses during the night, and told him, in no uncertain terms, to take his
people and get the #%$&@ out!
When it came right down to it, it wasn't an escape. They were driven out.
You could look it up. Around Exodus 12:30-34 for a start.