Goofs

When Jill has a drink at the wet bar, the grandfather clock is visible in the shot, about a foot to the right of the bar. In all other shots the clock is about four to five feet from the bar, much closer to the hallway.

When Curt Duncan Tony Beckley) is beaten up at the bar, the guy who did it pours a bottle of liquor over his body, soaking Duncan's shirt. When Duncan almost immediately shows up at Tracy's (Colleen Dewhurst) door, his shirt is dry.

Based on the year the film took place, 1 minute would not be nearly long enough to trace Curt's call. Back when the movie was set, it would've taken 10-20 minutes for several switchboards and circuits to locate the origin of the call.

It is not clear how Curt Duncan was able to track down Jill Johnson after she was married, presumably under her husband's last name, and know that she and her husband would be dining at the fancy restaurant that he called to have her paged.

Actually, it's pretty evident that the newspaper he picked up from the street contained had Jill's picture and married name in it, as she was chairing a "Community Fund Raiser".

Tracy doesn't close the door behind her when she lets John Clifford, the detective in her apartment.

Apparently she doesn't mind not closing her door as she also left it open when she went to answer the telephone while Curt Duncan was there. Once might be considered a character error, but twice makes it a character trait.

It is not clear how Curt Duncan was able to break into two apparently very secure homes undetected.

"Not being clear" does not constitute a Goof. It's possible Curt Duncan was a savant in picking locks or occupants simply left doors or windows unlocked.

Although it is most certainly not the actor's Tony Beckley) fault, but because he was terminally ill during production, the killer Curt Duncan looks far too physically frail to have realistically torn two children apart with his bare hands.

Duncan may have been more physically imposing seven years earlier when he murdered the children. He is not seen by the viewer until he escapes from the mental institution.

Stunt doubles of both men visible when John Clifford is chasing Curt Duncan through the mission. Charles Durning's stunt double is seen running up the stairs, and his face is visible when he bursts through the double doors. Tony Beckley's stunt double then tumbles down the stairs while trying to escape in the crowd of men.

Towards the end of the film, during an establishing shot of Jill's house, a crew member is seen in the bottom left hand side of the screen.

(at around 44 mins) When Tracy is getting Curt Duncan to leave her apartment, as she's closing her door, a part of equipment or a crew member comes into the frame on the left side.

Several scenes have C-Stands, lights and flags visible, most notable at 22:31, 36:22, and 1:31:49.