Personale o equipaggiamento visibile: Reflected in the glass behind Gittes while he signs the contract with Mrs. Mulwray.
Anacronismi: Police cars use the higher-pitched style of siren commonly heard from the 1960s onward, not the lower-pitched style characteristic of the 1930s.
Audio/video fuori sincrono: The tires squealing when Gittes pulls into the driveway of Katherine's house.
Personale o equipaggiamento visibile: When Gittes visits the orange grove and crashes into the tree, you can see that a steel plate has been placed around the tree to protect it.
Continuity: Gittes lights a cigarette while waiting to see Yelburton for the second time. Entering his office, he still takes a puff. But when they shake hands, the cigarette is gone.
Revealing mistakes: At the end of the movie, the cop shooting towards Evelyn's car starts stooping on his own, before Gittes coming from behind has a chance to grab him.
Anacronismi: When Jake gets home after following Mrs. Mulwray and his phone rings, it is clearly not the sound of a 1937 telephone. The sound of his placing the receiver on the cradle is authentic, but the ringer is no earlier than the sixties.
Anacronismi: Among the items in Ida Session's pocketbook, which Gittes rummages through is a social security card which is 1970s style with blue and red ink, not the 1937 style which had only one color, and a different look.
Continuity: When Gittes get drenched by the water, he's completely immersed in it. Then moments later his suit is fairly dry looking as though he had only been splashed.
Continuity: In the orange grove scene, Gittes car has its right front tire shot and deflated, yet it is not deflated when the car hits the tree.
Anacronismi: In scene with Gittes, Mulvihill, and Yelburton (“Mulvihill! What are you doing here?”), elevator call buttons are modern, automatic elevator type--they have lights. In the 1930's, elevator call buttons were generally black and had no lights.
Continuity: When Cross and Gittes are lunching, the close-up of Jake's plate does not match, with the fish, potatoes and lemon wedge being in completely different positions.
Errors made by characters (possibly deliberate errors by the filmmakers): When Gittes is driving through the orange groves, the sign says "No Trepassing." "Trepassing" should be spelt "Trespassing."