Revealing mistake: Harry Osborn types "Special Projects" (and we see the word taking shape as he types) hitting as the last keys "E", space bar and "G." (01:28:05)
Revealing mistake: During the battle of Dale, Bard confronts Alfrid, who is dressed as a woman and is trying to escape with looted gold. During the confrontation a troll climbs over the parapet and is killed by Bard. As the troll falls, Alfrid also falls. When he lands, the ground near his hand ripples like fabric covered in sand.
Revealing mistake: Crawling through a fire cave you can see propane bottles in the background several times.
Revealing mistake: In the POV shot from Thomas, capturing Bill and Ben puffing away from the water tower, Thomas seems to be off-centered from the tracks, making it seem like he is derailed.