There is an opinion that Moshe is left out of the Hagada so that one would not make a mistake and confuse him with God or try to turn him into a deity (it is for this reason that we do not know his exact burial place as well).
However, if you check your Hagada, you will find that Moshe is in fact mentioned right before Dayenu in a quote from Rabbi Yossi HaGlili about the multiplication of the ten plagues: (Shmot 14:31) “B’nai Yisrael saw the great hand which God wielded against Egypt. The people feared God and believed in God and that Moshe was his servant.”
How do we reconcile these two opinions?
In the Mechilta D’Rabbi Yishmael where this quote from Rabbi Yossi HaGlili comes from, only half of Shmot 14:31 is quoted: “B’nai Yisrael saw the great hand” and the part about Moshe is left out. It is also left out in the Mechilta of Rabbi Shimon Bar Yochai, Midrash HaGadol, Seder Rav Amram, Siddur Rav Sadia Gaon and from the Hagadot of Yemen as well as earlier Hagadot.
According to Shmuel and Zev Safrai, Moshe’s name is not officially considered to be in the Hagada as it was added later.
Although he is not specifically mentioned in the Hagada, in the discussions that go beyond the text that take place at most seders, especially when children are involved, Moshe is included as an integral part of the story of the Exodus.
According to the Rambam (Maimonides) in Hilchot Chametz uMatza 7:2, “It is a mitzvah to tell the children about the Exodus even if they do not ask…If the children are mature and wise, tell them all that happened to us in Egypt and all the miracles that God did for us by means of Moshe…”
Many seders today add in songs that help the children understand the story better. Many of these songs in both Hebrew and English mention Moshe including “Where is Baby Moses” and “Moshe baTeva” as well as the famous “Let My People Go.”
As long as those attending the seder are aware that God was the redeemer and that Moshe, Aharon and Miriam were there to help Him carry out the redemption there is no problem mentioning them and telling their story actually enhances the seder.
As it says in the Hagada “The more and longer one expands and embellishes the story, the more commendable.”