Continuity mistake: When Velvet and her mother are sitting and talking in the attic, her mother pours some gold coins into Velvet's lap. Velvet is sitting back on her feet, but a few seconds later, she raises up on her knees to hug her mother. The coins should go spilling everywhere, but we never see or hear them.
Continuity mistake: When the maid is out on the street calling a cab, the policeman shows up. The distance between them changes from close to farther away, between shots.
Continuity mistake: At the end of the film, Lieutenant Perry orders two men to take the Vickers .303 machine gun into the Frenchmans cafe. It cuts to a close up of the gun, which shows it's a WW2 era Vickers with a smooth water jacket. The men run and pick it up, and carry it into the cafe. When the scene cuts to inside the cafe, the Vickers has suddenly changed to a WW1 era Vickers with a fluted water jacket, which it stays as for the rest of the film.
Continuity mistake: Dick Powell puts his gun in his left trenchcoat pocket and then 2 minutes later takes the same gun out of his right pocket.