When the officers rent the flat, Kate gets up from the couch to answer the door, and she is wearing black heels. When she lays on the couch again, she is wearing lighter-colored flat shoes.
Rocky and Dan leave Romano's in a 1949 Ford squad car, but when they arrive at the night club, they are driving a pre-war junker.
In the final shootout, Garris fires eight shots and Dan fires seven shots, each from their six-shot revolvers and each without reloading (Garris was seen to possibly reload before his final eight shots).
At the end of the car chase, there is a shot of the car running off the road and hitting a tree. The shot from behind the tree shows the police in a different car from the police sedan in the other shots that has a large siren on the passenger side fender. The police car in the crash shot appears to be a Ford station wagon with wood trim on the side. It does not have the siren on the fender.
After the officers move in and are mounting things on the wall, the wall above Kate is seen to shake as if the hammering was on the other side of the wall. This would not be possible as the wall was not a common wall between the rooms- Kate had to go outside and then into the other room, and the breezeway was between the walls.
Wires are visible on the little girl at the climax.
In the final shootout, Garris gets "hit" a split second before Puris fires that shot that hits him. Donald Buka (playing Garris) reacts (throws his head back as if shot) ever so slightly before Edmond O'Brien (playing Purvis) fires his "killing" shots.
In the final shootout, Donald Buka (playing Garris) looks up at the corner above him a split second before the "bullet" from Purvis's shot chips and knocks out a piece from the corner (as if he was expecting the piece to be "shot off"). That must have been Buka's cue to move out into the open in the hallway so that Purvis could get his "killing" shots.
After Rocky leaves to get Kate, Dan sits down on a chair. The shadow of the camera is seen moving across him.