When briefing on the case at beginning, picture of victim in church was taken from high angle with very small blood pool; last shot of victim just after crime has priest holding victims head with huge blood pool already spread out.
Early on Fr. Kendellen comments that next week is Ash Wednesday and later, Meg Collins, the wife of one of the victims states that next week was supposed to be Sophia's 1st Communion; the Catholic Church does not celebrate 1st Communion during Lent.
In his flashback, Connor O'Brien sees himself reading a book as a child. The book he is reading is one from "A Series of Unfortunate Events". The series started in 1999, only 11 years before the air date. Connor is 30, leaving a nine year gap between when the first book was published to when he would have been able to read it.
J.J. spends most of this episode in the victim's home with his wife and daughter. The house should be filled with fellow mourners, considering their affiliation with the church.