In his limousine, Crowell dictates a message on a recording machine, then removes a cassette tape from the machine and hands it to Marlowe, who puts it in his chest pocket. A moment later, Marlowe puts the same tape in his chest pocket again.
Hicks is fully clothed when found by Marlowe. This is not the case when police arrive to investigate.
Marlowe pours whiskey into the waste basket to help burn the pictures and negatives. Whiskeys are not flammable unless they are greater than 100 proof (50% abv). Typical whiskeys of that era were 86 proof.
When Marlowe leafs through the registration book of "The Infinite Pad", all the pages are identical.
After Marlowe is attacked by three henchmen, when they jump in a car and the car and back up, a reflection of the crew and camera can be seen in the car window.