Continuity mistake: A sweaty knifeless Kasper Gutman places the Maltese Falcon back up on the table after they find out it's a fake, but in the next shot they show him holding the knife again. (01:29:35)
Continuity mistake: Kasper Gutman stands in front of the Maltese Falcon and demands the $10,000 back from Spade. If you look closely the falcon is untouched without any knife marks on it. (01:30:50)
Visible crew/equipment: At the end of the movie, Kasper Gutman gets ready to leave and as he passes in front of Brigid O'Shaughnessy an equipment shadow appears on her head. (01:31:15)
Visible crew/equipment: After the ship's captain delivers the Falcon to Sam Spade's office, he collapses on the leather sofa in the foreground. Just after Spade's secretary says, "Is he ...?", the shadow of someone's head passes over the sofa.
Audio problem: When Effie says on the phone to Archer's widow "no, not yet" her lips do not move.
Continuity mistake: When the two other detectives are interrogating Sam in his house, he keeps changing place.
Revealing mistake: In the final scene where Miss O'Shaughnessy is in the elevator with the detective, the door closes and the elevator starts to 'descend', indicated by dark glass going down, supposedly because the lighted elevator is passing beyond the view of the exterior door. But if you look, you can still see the silhouette of Miss O'Shaughnessy behind the glass, not moving. It is just a piece of wood or something being lowered behind the glass to simulate the elevator going down.
Revealing mistake: In the last scene when O'Shaughnessy is being taken down in the elevator, one can tell that the elevator is not descending: rather something opaque is being lowered (like a window shade) to make appear as if it is descending. If you look closely through the translucent outer elevator door both the scissor-door pattern of the interior cab gate and the outline of O'Shaughnessy's torso remain stationary and don't descend.
Character mistake: When Spade leaves Brigid in her hotel room, he says he will buzz her buzzer long-short-long-short, so she will know it's him. When he does return, he only buzzes long-short.
Continuity mistake: As Sam Spade slaps Joel Cairo, Joe's bow-tie changes from polka dots to stripes.
Factual error: In the opening credits, it says that the Knights Templar of Malta paid tribute to the King of Spain with the Falcon in 1539. The Knights that were in Malta were the Knights Hospitallers of the Order of St. John of Jerusalem. They mixed with the order of the Knights Templar, which went out of existence in 1314 and has also been founded in Jerusalem. They had nothing to do with Malta.
