Visible crew/equipment: When the mine cart crashes into the wall, you can see cables beneath the cart. (00:33:10)
Factual error: When Sean is crossing the chasm by jumping on the 'magnetic rocks', he jumps onto the edge of several of the rocks. Assuming that the rocks could actually float in the magnetic field as shown, standing on the edge of one of them would cause it to immediately flip.
Factual error: The crater of Mount Vesuvius has been fully blocked with rocks and soil since its last explosion few decades ago. There are no openings in it and no geysers shooting out.
Continuity mistake: In half a second, Leonard's hair swaps from messy to brushed to the right when Trevor arrives at the lab, despite him having both hands busy.
Continuity mistake: When the movie begins, Trevor enters the lab and his pal is holding the frozen object with his left hand. Half a second later he holds it with the opposite hand.
Answer: A mountain.