1)
Why did Hashem mention these other salvations?
1.
Malbim #1: You should have known that you still need Me.
2.
Malbim #2: Since I expelled them due to you, you should not have done like their deeds!
2)
Whom did Hashem expel?
1.
Radak: It was not Egypt, only Lochatzeihem - Sichon and Og, who refused to let Yisrael pass and came to fight them, Kena'ani Melech Arad (Bamidbar 21:21-35, 1-3) and Malchei Kena'an (above 4:2,3).