The screenplay for The Last Supper was created by Constante Diego, Tomas Gonzalez, and Maria Eugiena Haya. While there is historical documentation that a mill owner recreated the Last Supper with his disciples and a revolt ensued, the screenwriters do a great deal of dramatizing of events that go unproved in the actual incident.

In his book The Sugarmill (New York: Monthly Review, 1976) Manuel Moreno Fraginals cites an incident in Cuba where the events from The Last Supper occurred. According to Fraginals, "His Excellency the Count de Casa Bayona decided as an act of deep Christian fervor to humble himself before the slaves. One Holy Thursday he washed twelve Negroes' feet, sat them at his table, and served them food in imitation of Christ. But their theology was somewhat shallow and, instead of behaving like the Apostles, they took advantage of the prestige they thus acquired in their fellow-slaves' eyes to organize a mutiny and burn down the mill. The Christian performance ended with rancheadores [men whose job it was to pursue and capture fugitive slaves] hunting down the fugitives and sticking on twelve pikes the heads of the slaves before whom His Excellency had prostrated himself" (53).

Fraginals's source, Representacion extendida por Don Diego Miguel de Moya y firmada por casi todos los duenos de ingenios de la jurisdiccion, en enero 19 de 1790, has no English translation, making further analysis of the source very difficult. At any rate, it is clear that the screenwriters do a great deal of dramatizing of characters in the film, especially with the slaves at the dinner table. That the document would have gone into such detail about the lives and ambitions of so many slaves that had committed such a wrong in the eyes of the slave society as revolt is near impossible. That the master would have allowed himself to be in such a state in front of his slaves is also highly unlikely, though not unproved. Sebastian's fate is also a fabrication, as the film implies that he runs to freedom while Fraginals makes clear that all of the slaves at the table were caught and decapitated. Other variations from the source include the fact that the film is set after the Santo Domingo uprising instead of before and that in the film the Count is clearly responsible for the uprising, while the source seems to blame the pride of the slaves.

The events that took place at the Count's sugarmill made the question of the place of religion in the life of the field slave a difficult one, as several books on how to best educate and convert the slaves were written in and around the time of the revolt.