In the bathroom scene, Nick calls Roxy "Rocky." He gets her name right later when he is talking to Katherine. [Character mistake.]

Where does the first cigarette Tremell smokes during the interrogation go? There is no ashtray and it's not on the floor - which you see quite a few minutes later. [Unless you can see the ENTIRE floor (which you can't in the scene) you can't say it's not there.]

The address listed for Catherine, on Divisadero street, does not exist in San Francisco - the street stops before it gets to that number. [This is very common in films. Just like using fake 555 phone numbers. It prevents people from dialing those numbers and visiting those address. Not a mistake.]

This is another movie where the cops are too dumb to go out by themselves. The woman who icepicks the first victim (we see) to death would have left enough forensic evidence on the scene to convict her ten times over - skin, hair, sweat, saliva, vaginal fluid, possibly blood, and they all contain DNA in abundance. She had vigorous, sweaty sex with this man and she didn't clean up afterwards (and she couldn't have done so thoroughly enough anyway) so she's left calling cards all over the place. She might as well have left a signed confession, but they can't even identify her. Sharon Stone, for instance, leaves her fingerprints (on the chair and fixtures in the police station) and her saliva (containing epithelial skin cells) on the cigarette butt she discards, also in the police station. She went there of her own accord and these artifacts are legally accessible by the police - but they don't even check! [Sharon Stone admitted to being involved with the man, so even if she hadn't had sex with (and killed him) that night, it wouldn't be impossible to find her DNA on him or in his bed and home. It's incriminating evidence, yes, but not enough to 100% say she's the killer.]

Right at the start of the film, look carefully at the pigmentation around her nipples, then look at the breasts of the women. You can tell who the killer is straight away. [Pigmentation of the areola - the area 'around the nipples' changes during sexual excitement and varies during the menstrual cycle. It can't be used for identification.]

During the car chase scene, he drives down some stairs or a pavement. At the bottom his license plate falls off, but in the next scene, it's back. [It is not the license that flies off...it is a NO PARKING sign. However, it is still a mistake because there is a dark area where the white California license should be.]