Plot hole: Peter goes into Carl's mind to save Catherine. When he's in there he sees the tank with the water nymph. On the tank are strange symbols which provide the FBI with the clue needed to find the latest victim. Makes sense so far. But, go back to the scene just after the FBI have captured the comatose killer and are looking in his basement. The FBI are looking at the contraption that the killer uses to suspend himself over the victim. On the contraption is the same symbol seen later on the water nymph's tank. Why didn't the FBI follow up the symbol then?

Continuity: When Peter is in Carl's mind with Catherine and is getting his intestines wrapped around the spit, the amount of his intestine on the spit keeps decreasing then increasing suddenly.

Revealing: In the scene where a bleached dead girl is lying on the table, you can see her breathing.

Revealing: When Carl lifts the dead girl out of the bleach bath, she moves her legs to the side to make it easier for him.

Continuity: When Carl is washing plates, he has a pile of clean ones stacked on the counter. He places a third one down onto the pile but when we see the pile there's only two, then suddenly three, without him placing another one down. However when the plate he cleans falls and smashes, there's just two in the pile again.

Continuity: Just after Peter has entered Carl's mind for the first time, it then cuts to Julie who is trapped in the water tank. The sprinkler turns on and she gets up - her blue shirt tightly tucked into her skirt. It cuts and suddenly all of the shirt is hanging out. In these same two shots, the sleeves on the shirt alternate from normal to suddenly rolled all the way up her arms.

Revealing: When all the police cars pull up and skid, outside Carl’s flat, you can see skid marks already on the ground in front, from previous takes.

Continuity: When Catherine watches television in bed, watch the photos and the badge that are tacked on her wall, by the bed headboard. They move around between shots.

Continuity: When Julie opens the car door after she thinks she has hit the albino dog, she leaves her car door wide open. It cuts and the car door is then only slightly open.

Continuity: When Julia is trying to figure a way out the cell, she starting feeling around the edges of the glass panels etc., and the ring that she wears on her left hand goes from only showing the gold band, to suddenly rotating to revealing the stone, between shots when she grabs the pipe.

Continuity: When Catherine is thrown to the floor in front of 'King Carl' she alternates to laying with her legs crossed, to uncrossed, four times between shots.

Continuity: When Julia is trying to figure a way out the cell, she starting feeling around the edges of the glass panels etc., and she then comes to the end and stands by the green bench which is at the side of the cell. Julia's black heels sit on the bench, but then when Julia notices the pipe and climbs up to attempt to pull it, in the overhead shot her black heels have vanished from the bench.

Continuity: When Carl has a victim laying in a bath of blood, in one closeup the woman's corpse has a long bloody scratch on her left arm. This isn't there in any other shots, just this closeup. The blood stains around the edge of the bath differ between shots too.

Continuity: When Carl puts the video of bleached girl on, he hangs up his white shirt. The way it hangs differs greatly between consecutive shots.

Continuity: In the scene where they show the killer in his bathtub (prior to the police catching him), the first shot is a side view of him in the bath tub and the bath mat is not laying flat. The shot changes to a different view, then back to the side view and the bath mat is now laying flat.

Continuity: When the level of the water in the cell is rising, you see the girl clawing at the window. When they cut back to her in the cell later, the water is at a lower level.

Continuity: When Catherine turns to see Carl with a victim in a bath of blood, watch the two vases on the windowsill. They change from being side by side, to at least a foot apart.

Visible crew/equipment: In one scene Julia is in the cell and the sprinkler turns on. It stops, then she goes to the glass panel and starts banging on it and yells "Let me the fuck out! Let me out!", and you can see the reflection of a cameraman with a camera trying to keep a low profile, as she runs across, banging and shouting this.

Continuity: After waking up from entering the mind of Carl, Peter starts coughing and he pulls off the cloth that was over his head, which falls off and down onto the table. In the next shot though, the cloth is now laying right under his chin.

Continuity: In the scene where Catherine enters Carl's mind for the second time. When she follows the young Carl into the house, he is doing the dishes. The large plate in his hand does not have any designs on it, however, when they show him putting the plate down on the counter, the plate has a flowery design. The plate already on the counter (which he puts the other plate on) has a flowery design on it, but between these same shots, the design on the plate totally changes.