Plot hole: The FBI agent (played by Vince Vaughn) goes into the serial killer's head to save Jennifer Lopez. 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? In fact, why didn't they try to find out where the hell he got the contraption in the first place? Doing either of these things would lead them to the information on the whereabouts of the latest victim. There was never any need for Jennifer to go into the head of the killer at all. Which makes the whole point of the movie irrelevant!

Continuity: When Vince Vaughn is in Vincent D'Onofrio's mind with Jennifer Lopez and is getting his intestines wrapped around the "contraption" the first shot shows a fair amount wrapped up, a second shot shows about half as much, and the third shot shows more, but not as much as the first shot.

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. Submitted by Twotall

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. Submitted by Hamster

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. Submitted by Hamster

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. Submitted by Hamster

Continuity: When Catherine watches The Fantastic Planet on TV as she lays in bed, watch the photos and the badge that are tacked on her wall next to the bed headboard. They move around between shots. Submitted by Hamster

Continuity: When Julie opens the car door after she thinks she has hit the albino dog, she gets out leaving her car door wide open. It cuts and the car door is then only slightly open. Submitted by Hamster

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

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. Submitted by Hamster

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. Submitted by Hamster

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. Submitted by Hamster

Plot hole: The whole reason Catherine enters Carl's mind is to learn the location of his latest victim. They still have not learned this when Catherine takes him into her head, but she goes ahead and kills him almost immediately without even asking him about this crucial information. Submitted by Twotall

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. Submitted by Hamster

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. Submitted by Hamster

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 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. Submitted by Hamster

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. Submitted by Hamster