Visible crew/equipment: During the campfire scene a Morlock attacks Weena, and drags her off. If you look at the top of the frame, as the Morlock drags her away, the stunt man's head can be seen, as he forgot to wear the head part of the costume.
Visible crew/equipment: The string holding up the "Fire Monster" to make it appear like it's standing upright is seen in a couple of shots.
Visible crew/equipment: During the debriefing meeting near the end of the movie, a boom mic is visible hovering over the meeting table. (01:11:40)