Incorrectly regarded as goofs: Harry always shoots into his left arm, and that's the arm we see infected, both in the car and amputated in the hospital, two reports to the contrary.
Revealing mistakes: In the pullback shot of Harry when his arm is missing, you can see under the sheets the outline of his left arm pressed up against his body.
Incorrectly regarded as goofs: When Harry calls Marion from the hospital she picks the phone up with her right hand and puts it on her left ear but when the camera focuses on her it's on her right ear. This is almost certainly a mirror shot, not a mistake.
Revealing mistakes: Whenever someone takes drugs and their pupils "dilate" you can see that it's a normal eye being distorted by a computer because the arc of reflected light also is distorted.
Revealing mistakes: When Sara is trying on the red dress but it won't zip up all the way, in the mirror behind her you can see the 'fat suit' used to give Ellen Burstyn the larger appearance.
Revealing mistakes: When the two ladies visit Sara and are outside sitting on a bench, you can clearly see at the right lower part of the bench the cotton trying to appear as snow.
Revealing mistakes: At two different times during the movie (when Marion, Harry and Tyrone are discussing the possibility of getting heroin from Brody, and when Harry is sitting around waiting for Tyrone to come back with Brody's heroin), records are supposedly playing, but the tone arms are in the 'up' position and the stylus is sitting above the record.
Factual errors: Sara is given multiple jolts of ECT while fully conscious. Real ECT patients are always anesthetized, and only one extremely low-voltage charge is administered.
Factual errors: Eyes are shown to dilate when shooting heroin, but opioids such as heroin actually cause miosis (pinpoint pupils).
Continuity: When Harry is waiting for Tyrone to return with the drugs, we can see Harry playing with a turntable. The shot of the turntable itself shows Harry's left hand on the record. In the next shot, his right hand is in the turntable.
Continuity: When Harry and Tyrone pawn the TV, there is a goose-neck lamp behind Mr. Rabinowitz that changes position between shots.
Continuity: The purse strap changes positions between shots when Marion heads to and enters the elevator.