When Marlowe approaches the telegram on the table in Adrienne's apartment, there is a cut and the telegram becomes less folded and more flattened on the table before he picks it up.
In the kitchen, Marlowe pours the rice into his left hand twice, presumably putting the rice in his left pocket. After he meets "Mrs. Kingsby," he drops the rice with his right hand.
Searching the house Marlowe goes to the bathroom and sees three bullet holes in the shower door, one high up and two lower down inches apart. He opens the door and the bullet holes in the tiled wall do not match with one high up, one lower down and the third much lower down.
During the office party scene, the group sings "Jingle Bells" but the key shifts suddenly in the middle of the song, probably due to two takes being joined together.
In the "El Paso" telegram from Chrystal to Derace, both of their names are misspelled. (Chrystal does not have the "h" in it, and Derace has two "r's" in it.)
When the drunk looks through the broken window of Marlowe's overturned car and Marlowe cold cocks him, later we see the drunk's body lying near the bottom of the overturned car. If he had been standing next to the bottom of the car (on its side) he could not have looked into the window.
When Marlowe returns to Lavery's place: there is a small clock in the living room that reads 8 PM. However a few minutes later as Marlowe climbs the stairs there is a wall chime clock that also reads 8 pm and then chimes 8 times. Apparently both clocks were rigged to read 8 pm which is a mistake. The living room clock should have been set for a few minutes earlier than 8 PM.
When Adrienne is taking care of Marlowe after the car crash, she hands him a mirror so he can see his injuries. As he is putting the it down, you can clearly see the face of a stage hand in its reflection.
In this movie, Marlowe's first name is consistently spelled "Phillip", with two l's. In the Raymond Chandler stories it is spelled "Philip".
Audrey Totter's character uses the word "deducted" rather than the correct "deduced."