Other mistake: Marlowe tells Lauren Bacall to start screaming in 20 seconds after he leaves the room, she does and Lash Canino is outside and hears her. He runs into the house and if you look closely the prop porch railing almost falls over as he runs by because the crew did not attach it properly. Later we see it again and it's attached properly. (01:41:35)
Continuity mistake: The next morning after going to Lido Pier, Marlowe walks into the waiting room of his office and Lauren Bacall is sitting there reading a magazine as she waits for him. The lighting on her changes and the picture on the wall behind her head is lowered about six inches between shots. (00:32:20)
Audio problem: The second time he's in Geiger's house, Marlowe goes into several rooms and turns on a light switch as he snoops around. The light does not come on until a fraction of a second after the switch has been thrown, and the sound of the switch being thrown does not happen until after his hand stops moving. (00:28:30)
Character mistake: When Lauren is playing roulette, she has $14,000 worth of chips sitting on red - if she wins, she gets double, $28,000; and if she loses, she loses all of the $14,000 - but the croupier is troubled and says to Lauren that she hasn't got enough to cover the bet, which is ridiculous; all her $14,000 chips are sitting on red, what more does she need? Even the head croupier is called in, and, after much chatting, all the other players are asked to take their chips away as only Lauren is playing this round, which is ridiculous: All they have to lose is $28,000; that's nothing for them.
Continuity mistake: Marlowe says to Eddie Mars as he's about to leave his office, " Oh, Eddie, you don't have anybody watching me, do you?" And the collar of Marlowe's shirt is tucked under his jacket. The next time we see it about a second later it's been ruffled up and is no longer tucked under his jacket. (01:10:20)