Notice the silhouette of the B-17 on the wall behind Sam Jaffe's head when the hired hands--Anthony Caruso and Sterling Hayden--are being paid off prior to the caper in Cobby's office.
All of the dialogue spoken by Alberto Morin, who played Eddie Donato, was dubbed in by another actor--probably because Morin, who was born in Puerto Rico, had a pronounced Puerto Rican accent and Eddie Donato was supposed to be Italian.
First feature film role for Brad Dexter in which he was actually credited as Brad Dexter. In his previous credited roles he was credited as Barry Mitchell, but for this film, director John Huston convinced him to change his professional name to Brad Dexter. Dexter decided to keep the name.
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, and along that same wall is a door leading upstairs. On the other side of the wall, there was no evidence of a door.
When the police enter Gus's diner, he turns the volume of the music up, but oddly he does it by turning the dial anticlockwise, which would normally turn volume down. When they go, Gus turns the volume down, again turning the dial anticlockwise.
When the police break into what turns out to be Louis' memorial service, the door swings open all the way and sounds as though it hits the wall behind the door. In the next shot, from the inside of the room, it is clear that there are people seated behind the door who should have been hit by the door crashing open.
Police Commissioner Hardy: In some ways, he's the most dangerous of them all. A hardened killer. A hooligan. A man without human feeling or human mercy.