"Burnt Match Man" wakes up with a power cable in his head and severs it with his chainsaw, but when he confronts Novikov the power cable is attached again.
The signs reading "nicht antasten" ("Do not touch") seem to be German language, but no German would use that terminology. The correct translation would have been "Nicht berühren!".
When the still alive nun in the corpse pile is neck-knifed (put out of her misery?), when the knife is withdrawn, there is no blood traces (spurt, nor blade smearing).
When the soldiers first enter the church there is a white sign in the background saying "Nicht antasten". Later in the movie the exact same sign appears again when Dimitri enters the doctor's private rooms (pay attention to the wear marks, they are completely identical).
Fir Suidema's name at the end-credit is misspelled as 'Fir Zuidema'.
The steel helmet worn by Ivan is in fact a Bulgarian M1972b distributed from 1972 onwards.
This film is made in the "found footage" style, where the viewer is supposed to be looking at real life footage that has once been discovered. And yet, all the Russian characters speak English among themselves.