Early in the film while Johnny Blake (Robinson) is sitting at a table with Joan Blondell talking, one of the old "mugs" he'd sent to Sing Sing prison walks over to him and smarts off. Without standing, he kicks the mug in the leg and punches him to the floor. While leaning over and chastising the unconscious mug, you can see that Blake's (Robinson) hair has moved forward on the right side and is messed up. In the next shot, when he leans back up to the table to talk to Joan Blondell, his hair is perfectly neat and combed.
When Nellie comes in to see Lee with the proceeds from the numbers racket in Harlem, she sets the bag down on the desk twice between shots.
When Lee is driving Johnny to the ultimate drop-off with the heads of the organization, headlights of traffic behind them can be seen through the rear window. When she stops the car to let Johnny out, there is no traffic behind or passing her car. In fact, the street is completely empty.
When Herman is delivering a bag of money to Lee Morgan, he takes out a roll of coins and covers it with his right hand so that it is barely visible. In the next cut, however, the roll is now protruding out of his hand and quite visible.
When Fenner and Kruger are in the theatre watching Ward Bryant's newsreel re-creation of mobsters collecting money from the nickel game machines, there are school children playing the machines. Later on in the real-world, when the police raid Schultz Drug Store and confiscate the nickel game machines, school children are also shown playing the machines. But the school children in the real world are the same ones used in the re-creation including wearing the same clothes.
The newspaper announcing Johnny Blake's firing is an obvious studio fabrication. While the central headline furthers the plot of the film, the smaller type below, in the same columns, is totally unrelated to the story line or the headline above.
When Blake returns to his residence, he runs into Wires sitting in the lobby reading a paper. Blake knows that Wires is a wiretap specialist and rightfully so becomes suspicious. But it makes no logical sense to also use Wires as a lookout after bugging Blake's room thus inviting a red flag. They could have just used a different person to spot Blake or have Blake run into him in the elevator or something as Wires was leaving. The illogical scene disrupts the flow of the story.
When Johnny Blake and the cop on horseback get into a fight, after the fight is broken up, the cop isn't wearing his badge.