Blooper

When Riedenschneider is first led back into Cobby's back room, there are three men visible through the door when it opens. When he gets into the room, they are nowhere to be seen.

When Louis and Doc finish emptying out the jewelry boxes, the vault gate is open. But after they crawl back out under the electric eye, the gate automatically closes. It makes no sense as to why the gate would close, especially since Louis crawled back and forth a couple of times without the gate closing.

The security guard's double-action revolver would not fire when dropped on the floor.

When Doll asks the railroad worker for help, he sticks his head inside the car, he tells her about the doctor up the road and the background moves as if the car is moving. But there's no physical indication that the railroad worker is holding onto the car; his head doesn't move and his hands aren't seen grabbing the car. He wouldn't be running along side the car with his head inside it.

Dix Handley is supposed to be a native of Boone County, KY but speaks with no discernible Southern accent. However, there are many folks from Kentucky who speak unaccented English.

When the police enter Gus's diner, he turns the volume of the music up, but oddly he does it by turning the dial counterclockwise, which would normally turn volume down. When they go, Gus turns the volume down, again turning the dial counterclockwise.

In the juke-joint scene, the music continues to be heard as the record machine is seen to be changing records.

When Mr. Ciavelli was inside of a long narrow tunnel, he chisels through the thin brick wall of the tunnel and goes inside of a room; along that same wall is a door leading upstairs. On the other side of the wall, there was no evidence of a door.

When Dix and Doll arrive at the Hickory Wood Farm in their car, the reflection of some crew members can be seen in the passenger side door.

When Doll is leaving Dix's apartment and they're talking on the stairway landing, there is a chain visible on the left holding up the false ceiling over the stairs.

Although the story takes place in middle America, one urban scene clearly shows the Los Angeles city hall in the background.

In order to break into the jewelry vault, precise timing was scheduled by the thieves. They had everything down to the minute. However Ciavelli had to break through a brick wall with a hammer and chisel. There was no way to predict/schedule how long it would take Ciavelli to break through the wall in order to let the other thieves into the vault area.

When Dix tells Doc about the alarms going off all over the block, he has entered the vault area where the safe box is. He then returns to the look-out station near the window. There is still an active electric eye, but Dix appears to have ignored it. The film doesn't show Dix crawling under it as the others did. Even if the film showed Dix crawling under it, it would have made no sense since Dix is 6'5" and served no purpose being inside the vault area. He could have said what he had to say from the other side of the electric eye.

The Professor has planned the burglary seven years earlier, just before he went to prison. But the plan is used as is, with no check made on whether the layout of the store or the security system has changed.

When unconscious Dix is being helped to the table in the doctor's office, Dix lifts his right hip to help get on the table.