The way Carey finally finds the whereabouts of the murderer - offering the dog piece of rope found in the garbage and running after it - has nothing to do with the detective work done throughout the entire game till that point.
The receptionist at the social services office identifies herself as Nora Hayes, but according to the game credits her last name is Bitteridge.
When Carey arrives at the theater via the back entrance of the mysterious house and finds there the unconscious woman, clicking the "eye" icon on the seats reveals that they are covered with red fabric - and red fibers were found on the victims' bodies. Carey should have noticed that when he first entered the theater from the front, after being invited to watch the movie, but clicking the "eye" icon on the seats at that time does not reveal anything special about them.
On Wednesday, when Carey arrives at the City Hall on 9:00 AM, Lieutenant Block informs him that third body has been found that morning in Griffith Park. Later, when Carey goes to the morgue, the deputy coroner Nobles tells him that the body has been found by the police park on 10:00 AM that morning.
In the Short Stop Bar there are two arcade machines, the right one is mostly occupied by someone who seems to play it for hours. However, if Carey tries to play either machine by inserting coins, the game comments that both machines are out of order (in the diskette version).
It is unlikely that only one field investigator (Carey) is assigned to investigate the serial murders, especially in view of the public pressure.
Carey enters the mysterious house by forcing his way in - prying open the metal double doors and then picking the lock of the wooden door, without asking anyone for permission and without obtaining search warrant first. Since Carey arrived that house by chance, not in hot pursuit, and none of the evidence he had picked earlier indicated that the murderer had anything to do with that building - he was forbidden of acting that way by police procedures. Furthermore, it was not safe to enter without notifying dispatch and without backup.
At the Social Service office, Carey takes from Luella Parker's room two file folders, of Barbie Cann and Mitchell Thurman, then asks Nora the receptionist about them. Since the folders contain confidential information, the receptionist should not have allowed Carey to take them, nor she could reveal any information about them, unless Carey presented a court order.
Carey finds a newspaper clipping in officer Garcia's car, after it has already been swept by SID. It is unlikely that they could miss such a conspicuous item.
On Thursday, the man at the check-in window of the impound lot tells Carey that the code is "McGarret said: 'Book him, Dano!'". The correct spelling of these names is McGarrett and Danno.
When John Carey unlocks the stage door, Mitchell Thurman knocks him unconscious. Rather than kill Carey, or at least bind him, Thurman just puts Carey on the floor with his guard dog. It makes no sense why Thurman does not seize the opportunity to kill Carey.
Dennis Walker invites Carey in his apartment. Why would Walker, who is a member of a Neo-Nazi gang, want a detective snooping in his apartment? Unless he planned to have his girlfriend attempt to murder Carey.
Carey falls asleep as a result of drinking the drugged tea Mitchell Thurman gave him. Thurman has a chance to kill Carey, but instead he wakes Carey up and sends him away. It makes no sense why Thurman does not seize the opportunity to kill Carey.
After receiving a call from Emmo Jones, Carey goes to the LA neighborhood at night, and soon he is caught in a shootout. The game wouldn't allow the player to put on the Kelvar vest before the gang member starts shooting at him. Carey wouldn't have enough time to put the vest on.
When Carey enters the murderer's house, he finds a severed head in the refrigerator. Later Carey is knocked unconscious by the murderer and stripped of all possessions, including the lighter he carried. After Carey regains consciousness, he finds the lighter in the mouth of the severed head at the refrigerator. It makes no sense why would the murderer put the lighter there.
The murderer's fate remains unknown. Although it seems improbable that he could survive after being torched by Carey, it is never confirmed that he actually died.
Except several facts which the receptionist at the social service office tells Carey about the murderer, nothing else is revealed about him - his background, motive, choice of victims, etc.
The identity of four of the victims - the anonymous bodies referred to as 1202-L and 7216-M, the unconscious woman at the theater and the man whose severed head is found at the refrigerator - remains unknown.
In the end, the mayor announces that Carey solved "a series of five homicides". Even if the murderer did not kill the unconscious woman, there was a sixth victim - the man whose severed head is found at the refrigerator, for the murderer did not behead any of the other victims.
When asking Chester about the "ambush ballistics" she will tell you about them. At the end of her dialog she laughs and says "I don't know" which wasn't edited out.