During the scene where Marlowe is chasing Mrs. Wade in her top-down Mercedes 450 SL convertible, the car goes from having head rests to having no head rests in various shots.
At the beginning of the film, Philip Marlowe opens the refrigerator to get food for his cat. There are two rows of eggs on the fridge's door, with one egg missing on the lower row. After a cut-away scene, Philip reaches for some eggs, but now there are several eggs missing on the lower row.
The ink handprints include the palm of Marlowe's hand, but it did not appear that the palm of his hand was on the ink pad.
A toothpick suddenly disappears from Morgan's (Warren Berlinger) mouth while he is driving Marlowe home from jail.
When the cat won't eat, the position of the cat and food dish change.
When Marlowe buys a newspaper from a vending machine, the headline on the front page reads "Jet hijacked". Moments later, when reading the same paper in the car, the headline has switched to "Rain of jet parts".
In fact, these are two separate newspapers; Marlowe picks the second up in the car.
When Marty Augustine and his henchmen are threatening to circumcise Marlowe, Augustine says "Harry, your father was a mohel", but the DVD subtitles read, "Harry, your father was immoral." A mohel (pronounced "moil") is a person, usually a rabbi, who performs circumcisions on Jewish males.
When Marty Augustine and his henchmen are forcing Marlowe to get naked, Arnold Schwarzenegger looks straight into the camera for a full second when he is about to take his pants off.
From the Mexico town funeral procession at 1:14:50 to the Malibu Beach party at Roger Wade's (via fade), there's a white spot that remains on the upper middle/right of the screen, continuing into the Malibu house room where the hippies are playing music, and then vanishing once Marlowe is chased by the dog outside at 1:15:30..
In the newspaper that Marlowe is reading while being driven home after his release from jail, his first name is misspelled twice as "Phillip" (two l's). While it is possible that a real newspaper would make that mistake, it is far more likely a mistake by the prop department. (It is also misspelled "Phillip" in the DVD captions.)
In all the radio ads promoting the movie, the announcer refers to the title as " A Long Goodbye".
Marlowe's initial line following Dr. Verringer's demand of $4400 from Roger Wade (in the hospital) appears to be dubbed. Marlowe lights a cigarette and does not move his mouth as the line is heard.
Boom mic and operator are reflected off a black car in Malibu Court.