One of the devil creatures jumps onto the flying helicopter. When the camera angle is from inside the helicopter the front pilot's door is closed. But when the camera angle is from the ground looking at the helicopter, the front pilot's door is partially open.
After the character is lowered into the hole to search for Stone and releases himself from the rope, you can see a carabiner attached to the end of the rope. However, a few shots later (as the character starts searching for Stone), the rope has no carabiner at the end but simply a loop.
When Simon is being arrested by the police crew, the camera cuts to a shot of Jayne and Lisbon. In the latter shot, Simon is seen in the background behind Jayne and Lisbon which indicates that this scene was filmed out of order and kept in the final cut of the movie.
The helicopter is supposedly registered "O-LEAF" VH is the registration number combination for Australia. "O" is the registration number for Austria.
When the character lowered into the cave finds his friends body, while scuttling away the cave floor at the base of the large stalagmite flexes under his arms revealing it to be a set.