Biggest plot hole
I liked the movie overall, and despite being fairly predictable in some spots, i thought it did a good job of keeping the tension high.
My biggest issue was with the fact that the cops didn't find his underground lair to begin with. So, they brought an entire SWAT team out to his creepy house, took one glance and saw nobody was in it, so they ALL left? They didn't search the grounds at all? I mean, some would leave to continue the case and follow leads, but a bunch would have stayed back to look for clues. Because they easily would have found the trap door in the ground (just as Jordan did) if they had done 10% of the work a normal police force does.