Revealing mistake: In the scene where Rose shines the flashlight down into the mine shaft, the light from the flashlight can be seen reflecting off of it, as if the lava down in the shaft is just a picture (or on a green screen).
Revealing mistake: As the miners are trying to break down the washroom door, the camera pans over the door frame from Rose's side to the miners' side. Just as it settles into its final position, you can see the sliding wall section they used to allow the camera to pan, sliding back into position on the left of the doorframe.
Revealing mistake: When the young woman's skin is ripped off by "Red Pyramid", you can tell from the texture of her skin, and the way it moves that it is fake.
Revealing mistake: When Christopher first meets Officer Gucci on the bridge, it is absolutely pouring down rain on and around them. However the river which they are just a few feet from is calm and not being rained on. I know that rain has to stop at some point, but they are on a bridge and no rain is hitting the water below the bridge.
Revealing mistake: When Rose first lights her lighter after the first transition to the otherworld, there is a bright orange light projecting onto her arm. Not only is it far too bright, but it is at an angle not possible given the way she is holding the lighter.