Continuity mistake: Montgomery's shirt, when he is ripping pages out of a book, is blue. However, when Azazello takes the gun from his hunting vest, his shirt is white.
Continuity mistake: When Douglas is first walking through the creature settlement, his shirt sleeves are rolled up. In the next shot from the same scene, his sleeves have gone down.
Answer: Science. More specifically, to prove that it could be done.
Phixius ★