@Meir Zirkind already pointed out a link to a website (that I had also found in searching) that discusses this inyun at length. I will write here in short what is brought there (at least the sources with the most weight without going into additional savaras and sources that are brought there.)
See Maharal in Gavuros HaShem that says the Pesach was eaten b'hasabeh.
See the Bach in Siman 475 d'h "csav achi" (Ois 7 in Machon Yerushalayim print) also that the Pesach was eaten b'hasabeh
See Shibolei HaLeket in Seder Pesach Siman 218 d'h "Zecher L'Mikdash C'Hillel" that says the Karbon Pesach was eaten b'hasabeh.
See Sefer Rosh Yosef that says also hasabeh was made by the Karbon Pesach
See the most interesting proof (not brought in the link that Meir Zirkind commented with) from Shir HaShirim Rabbah (1:3):
"Amar Rebbe Avahu ad sh'Moshe V'Yisrael Masubin V'Ochlin Pischaihem b'Mitzraim"
The Pri Megadim however writes in Siman 477 A"A Sif-Katan 1 that he didn't find in the Rambam that one has to make hasabeh. They are m'diyak in the Rambam Hilchos Chometz U'Matzah Perek 7 Halacha 8 that from there we see that hasabeh wasn't made by the Karbon Pesach.