What is the "Ra'ah" to which the Egyptians would refer?
Rashi (10:10) and Targum Yonasan: It is the star (planet) Mars. 1
Why was Moshe concerned about what the Egyptians would say?
Rashbam: He was worried about the desecration of Hashem's Name. 1
When the Egyptians would comment "We told you so!"
What is the significance of the mountains where Hashem would kill them?
Riva and Hadar Zekenim (in Pasuk 11): It means that Hashem held Har Sinai over their heads. He tends to [threaten] in this way - like we find by Matan Torah. 1
Targum Yonasan: He was referring to the mountains of Tavor, Chermon, Siryon and Sinai. 2
Oznayim la'Torah: Because it is a location where it will not even be possible to bury them.
