When Arturo Dos Santos comes to pick up the children at their home, he drops an ear of corn. As the view shifts to the rear of the scene, he immediately drops the same ear of corn again.
The narrator opened the scene at Fatima saying, "Here we are in the mountain village of Fatima on Sunday, May 15, 1917." That Sunday was on the 13th of the month, and the lady asked the children to return for six months in succession on the 13th day to the Cova da Iria, as the movie indicates.
Some words, some pronunciations and name of characters (like Arturo Dos Santos) are in Spanish, not Portuguese. He would be Arthur (or Artur) dos Santos. The same in Maria Dos Anges. Anges is French; in Portuguese, the name would be Maria dos Anjos.
Some costumes look Mexican or Spanish, not Portuguese.
Just before the first vision occurs, Jacinta picks up a little lamb and holds it all the way through the vision. Frontal shots (from the lady's POV, showing the kids looking up) show her holding an actual lamb. Shots from the rear (showing the three children before the bush with the lady on it) show Jacinta (Sherry Jackson) holding an obvious wooden or plastic model.
The Lady told Lucia to learn how to read and write so she could spread God's message. When the administrator took them away in his car, Lucia was able to read a signpost indicating that they were going to the next town.