Is it true that there are some substantial objections to the Last Supper being a Passover meal? If there are any, how do you respond to these arguments?
There are some objections that are commonly made to the Last Supper being a Passover meal, but very few of them are made in light of Yeshua’s words to His Disciples: “I have earnestly desired to eat this Passover with you before I suffer” (Luke 22:15). According to the Messiah, the meal that He ate with His Disciples was the Passover, and what may appear to be divergent accounts among the Gospel authors need to be theologically reconciled. The text does not say that He just celebrated the Passover, but specifically that He ate (Grk. esthiō) a seder meal. And while we commonly consider “Passover” to just be a holiday, in Scripture the pesach can be the “sacrifice.”
Some objections to the Last Supper being a Passover seder include the references to it occurring on the Day of Preparation (John 19:14), Passover eaten with solely a group of men as opposed to a family, the fact that there is no distinguishing between “bread” or “unleavened bread” in the accounts, and wine being consumed from a common cup. In contrast to this, the meal was eaten at night as the Passover should be, the obligatory drinking of wine was remembered, Yeshua and the Disciples customarily reclined for the meal, and a hymn was sung as was observed for Passover (Matthew 26:30). They do appear to have followed the prescribed protocol for a First Century Judean Jewish Pesach.
In total, it does seem that some modifications were made between Yeshua’s seder meal and the main seder that would have been observed during His time. There have been various proposals made for this, including the thought that Yeshua’s Last Seder was a “teaching seder” held between a Rabbi and students, or quite simply that the Lord held His Last Seder a day early as He was preparing to be sacrificed.
 CHALOT, 294.
 For a brief examination of this issue, consult the article “The Last Supper and the Passover” in Duane A. Garrett, ed., et. al., NIV Archaeological Study Bible (Grand Rapids: Zondervan, 2005), 1611.
Also consult the editor’s article “The Last Seder and Yeshua’s Passover Chronology.”