The actor who plays Gregorio, Marino León, was an immigrant from Huancavelica when the directors and producers discovered him. He was reading a book in a classroom that was full of kids, at a school in Lima. Stefan Kaspar and Fernando Espinoza looked around the classroom searching for somebody who could play the role and then they saw Marino. They asked the teacher to tell Marino that they would like to talk to him. They talked to Marino in Quechua and Marino told them that he could understand Quechua, but he could also understand Spanish. At that age Marino was already bilingual.
At the end of the movie, when Gregorio says "There were more than 20 000 soles and who was I supposed to give it back to?", he is talking about an old form of currency used in Peru. In 1984, when the movie was first released, 20 000 soles was like 100 new soles. Peruvian currency changed its name several times, first it was called "Soles", then "Intis" and then "New Soles". Peruvian people have been using "New Soles" since 1991 as the national currency. But this relatively new currency is commonly called "Soles" because it is shorter.