The second portion of the film is set in Missouri in 2018, however the recording of Lasombra's interview with Davara is dated as being from 2017 on his phone screen.
When Detective Villiers and Jason meet after the cultists' attack, the clock on the wall behind them does not change from 8:53 pm, despite at least a minute passing.
In the 114th minute James is driving in the rain, but from inside his car there is no rain falling on the windshield.
Tourism in Bhutan is strictly controlled and tourists must have a Bhutanese guide. It would have been near impossible for tourists, or other foreign visitors, to travel by themselves in the way portrayed in the movie.
Loons call (cry) at dusk, not at night, as when James is chased by the cultists.
In the opening act, while in the cabin; one of the hikers puts some water on the stove - the sound of a whistling kettle can be heard, to indicate that the water is boiling; but there is no whistle attached to the spout.
The film is set in the US but was largely shot in South Africa and the overseas shooting is inadvertently revealed when the protagonist looks at a blank VHS tape. It's an E-180; videotapes of that format used in America would begin with "T" (e.g. T-180). The E prefix stands for "European" and is used for PAL/SECAM systems; the T prefix stands for "Television" and is used for NTSC systems.
When James visits Greg in the hospital, before he slides the door open, he knocks his arm into a black cloth, which sways after.
In the 115th minute when James is speaking with the nurse, in the shots from behind the nurse's her face is not moving as she is speaking.
When James crosses the bridge at the camp, in one shot, the camera shadow can be seen in the bush.