The events that would be the uppermost in Jews minds during the Passover meal today would be the remembrance of the deliverance of the Israelites out of bondage in Pharoah's Egypt and the remembrance of the killing of the first born of the Egyptians. God visited 10 plagues upon the Egyptians, but in the case of the killing of the first born, God 'passed over' the dwellings of the Israelites and they were unharmed during this plague.
There is a spiritual application today as Passover is a remembrance of coming out of bondage to sin.
God instructed that the Israelites sacrifice a lamb without blemish as part of the first Passover. They were to take some of the blood of the sacrificed lamb and place it on the two doorposts and the lintel of their house.
Law of Moses