Pifias

Hugh Grant's character acts as if it's a given that the girls are familiar with Radiohead's "Creep"... But the use of smartphones shows the movie is happening in the present day time and the girls are in their early 20's. The song came out in 1992, close to the time of the girls birth. Especially if they came from a religiously conservative household, its very possible they would have never heard it.

A woman who was starved and in a weakened state as the captive women were wouldn't have had the strength to open the metal trap door, move the dead weight of a dead body and dump it down the shaft. Also the body was not near the base of the ladder so it would have had to have been dragged after being dropped. All that would have had to have been accomplished without making noise to alert the girls that it was happening.

Grants character listed the Egyptian god Horus as being a previous iteration of Jesus and mentioned 12 disciples and resurrection. However, there was never a clear number of defined followers for Horus. Also the death and resurrection story is more closely associated with Horus's father Osiris.

As Mormons are one of the only religions going door to door, a point made in the movie, that many Mormon women missionaries disappearing would have been noticed. It's clear that Grants character's real address is available/known to the church bc the male elder shows up there trying to find sister Paxton and Barnes. The fact that Grant's address was common to all the missing women would quickly become clear to the church and authorities if that many missionary women remained missing. The number of women sister Paxton finds in the room definitely qualifies as serial killer level.