Goldy brings Helen a pot of coffee with cream pitcher, sugar bowl and one cup. After talking to Gay, Helen throws the bowl, pitcher and pot but nothings spills out of them they are empty.
When the Falcon glimpses the room number for the "scientist" in the hotel, it's easy to read the number 506 in the book. However, when he later enters the scientist's room, the number 516 can be clearly seen on the door.
When the police arrive to where Max Carlson was killed, O'Hara turns on the lights in the room. But the power to the lights had been cut earlier when a circuit breaker switch was flipped. The switch had not been flipped back, so there should still have been no power to the lights.
When George Sanders is punched by a policeman on the street, it is obviously a stunt man who gets knocked down and stands up, not Sanders.
It is obviously a stunt man who is knocked down as Goldie, not Allen Jenkins.
At the florist shop, there are visible defects in the wall above the table where The Falcon is sitting that are where the squibs are located.
At the florist shop, four shots are heard, but there are only three holes in the shop's glass door and three holes in the wall where The Falcon had been sitting.
The rear projection footage used in most of the driving scenes was shot in Los Angeles, although the film is set in New York City. This is evidenced by the Biltmore Theatre in Downtown, LA appearing in one scene. Also visible are the L.A.'s iconic and unique cast iron double streetlights from that era.
When The Falcon is in the flower shop, Goldy is standing outside the shop with his back to the store window. But when the gunman fires three shots into the store Goldy doesn't react at all; he just stands there. even though his boss is being shot at.