Continuity mistake: Jake walks back into his office after getting a shave at the barber shop and his hair is combed backwards. Later in the scene as he tells the joke about the Chinamen his hair is still parted in the middle but combed sideways to the left and right. (00:18:30)
Continuity mistake: The left side of Barney the barber's bowtie is tied differently between shots as he gives Jake a shave. (00:17:10)
Continuity mistake: As Jake gets a shave in the barber shop we see the picture he took of Katherine Cross and Hollis Mulwray in the newspaper. If you look closely it's obvious that these are not the same actors we saw in the previous scene. (00:16:20)
Continuity mistake: In the barber shop as Jake gets a shave look closely at the shaving cream on his face. In the first shot it reaches all the way up to his lower lip, but when he gets out of the barber's chair to yell at the banker, it's nowhere near his bottom lip. (00:17:05)
Continuity mistake: When we see Katherine Cross and Hollis Mulwray's reflection in Jake's camera lens, Hollis is standing in a different spot than we saw in the shot before. In the reflection he's in front of the chair but in the previous shot he was next to the chair. (00:16:05)
Factual error: Duffy rows Jake around Echo Park and if you look closely you can see some late twentieth century street lights in the background. (00:14:10)
Continuity mistake: Hollis Mulwray rows Katherine Cross around Echo Park in a rowboat. When we first see them her hands are in her lap but in the next shot her left hand is touching the side of the boat. (00:15:20)
Continuity mistake: When Jack says to Curley, "Enough's enough", the statue to the left of Jack moves in front of the picture of Franklin Roosevelt between shots. (00:02:35)
Continuity mistake: Jake follows Hollis Mulwray out to the ocean. In one shot he's standing in front of some boulders then in the next shot Mulwray's out near the water about 50 feet further. (00:11:00)
Continuity mistake: When Jack's trying to outrun the guys shooting at him, they shoot his tire, sending the trim ring flying. However, when the car nails the tree, the tire looks completely undamaged and the trim ring is back on.
Continuity mistake: At Hollis Mulwray's office look closely at the drapes behind his secretary as Jake first walks in. No one goes near them but by the time she gets back to her desk they've been rearranged. (00:51:25)
Continuity mistake: After leaving Evelyn Mulwray, Jake goes to the Oak Pass Reservoir to look for Hollis Mulwray. If you look at the design on his tie, it's obvious that it has been re-tied. (00:31:30)
Continuity mistake: When Mayor Bagby speaks at the water and power meeting the map behind him curls up on the left in some shots and not in others. (00:06:00)
Continuity mistake: There's a very cool shot of Katherine Cross and Hollis Mulwray's reflection in the camera lens as Jake takes their picture from a roof top while they're having lunch. The problem is as the cameraman zooms in, Jake's hands are shaking but the reflection in the lens doesn't. (00:16:05)
Continuity mistake: In the very first scene of the movie Curly looks at the pictures of his wife that Jake took. He gets to the fourth picture and rotates it 45 degrees to get a better look. As he goes on to the next picture he lifts the fourth one up, and in the next shot he's holding a different picture. (00:02:00)
Visible crew/equipment: When Gittes goes to Evelyn's house before she tells him the truth about her and Katherine, one of her servants opens the door and you can see in that precise moment the shadow of the camera on the door jamb on the left and on the wall next to the stairs while approaching to the actors. (01:47:23)
Continuity mistake: Gittes finds Mrs. Mulray's big house being shut down, finds the eyeglasses in the saltwater pond and races to the small house where Mrs. Mulray's daughter had been staying. All their luggage was there at the small house because they were leaving there to go directly to the train station to make their escape to mexico. The Mulray entourage (daughter and servant) hurriedly leaves the smaller house without their luggage since Gittes had called the detectives. After Gittes takes the detectives on a deceptive trip to Curly's and eludes the detectives by Curly driving away with him, the next scene has Curly and Jake putting the last of Mrs. Mulray's entourage's luggage into Curly's truck in front of the Mrs. Mulray's large home, not the smaller house where the daughter had been staying and where they had all their luggage together to go straight to the train to escape to Mexico. The sequence should have had Gittes retrieving luggage from the smaller house.
Other mistake: While reading a book in the Hall of Records, Jake notices some names are pasted in. One of the pasted in names is spelled "Clarence Speer." The name comes up again as Jake Gittes and Evelyn Mulwray are driving away from the orchards. The name is spelled in the subtitles "Clarence Speer" and Jake pronounces it "Clarence Speer." Later Jake and Evelyn are reviewing the Mar Vista Rest Home Activities Board. Here the name is spelled "Clarence Speers." (01:07:35 - 01:17:25)
Audio problem: At 1972 Canyon Drive, Jake pulls into the driveway and the sound of screeching wheels continue even after the car has stopped. (01:47:10)
Revealing mistake: When Jack Nicholson slaps Faye Dunaway, the first time we can see he doesn't actually hit her. We see a shot of him raising his hand, then a shot of her jerking her head like she was slapped, but his hand doesn't touch her, or even go anywhere near her.
