Kira wrote: It says very clearly that G-d's intention wasn't simply to get the Jewish People out of Egypt. The main purpose of all the fireworks was "so that they will know that I am Hashem". The Egyptians, not the Jews. The Jews also, but mainly the Egyptians.
As far as we're concerned, at the Seder we say a poem with the refrain "It would have been enough" - at each step of the Redemption, we say, "It would have been enough". So, whatever steps G-d would have included, there would have been a Passover for us to thank Him.
In terms of Moshe lying -there are a few good answers, including: everyone understood what was being said, just it's not something that should be said out loud to a king. But it's not like there were any illusions. Moshe never said that they would come back. He did say "a journey of 3 days, and we will worship our G-d". From there to Sinai is indeed a journey of three days (the fact that it took them over a year is not a function of the distance). -Kira
Thanks Kira, I appreciate your explanation.