Scene of the CrimeGoofs
After Sleeper surprises Conovan and his wife by hiding in the back seat of the car, there is a fairly tight shot of Sleeper looking down at his fingers and rubbing one fingernail with another as he speaks to them. Then the shot pulls back to show Conovan and his wife more completely in the front seat, and suddenly Sleeper's fingers are folded together as his arms rest on top of the front seat.
When Detective Lieutenant Conovan visits the slain Detective Monigan's son, the late-teenage son bitterly mentions Monigan's birth date as "July 25th, 1922," which, in the film's present-day setting of 1949 would have made Monigan 27 years old. The actor portraying Detective Monigan looked to be at least in his late 50's or early 60's.
When Detective Piper introduces the young man that sold the .38 S&W revolver to the cop killer to detective Conovan the man says he sold the gun to a man in a bar. Conovan then grills the man about his getting a lousy eighty bucks for the gun that killed his former partner. But at no time did the man mention getting eighty bucks for the gun.