When one of the victims gets her throat slit with a piano wire, we see blood running from her mouth and onto her chin - however between shots, we don't see the woman spitting up the blood.
When the nude girl gets slapped by the Nazi, a drip of blood appears on her lips. Next shot, it has trickled down to her chin.
The white Mercedes driven by Fulci is a late 80s E-Klass, but in the footage of the chase it is a quite larger late 70s S-Klass.
When hooker is killed next to the road, when killer is shown, behind him is dark, but when she is shown, behind her it's day.
The footage being played back of a woman getting her eye gouged out has a different scream than the first time.
Obvious use of a cat puppet when it eats the brains; notably the eyes.
A lot of victims in this movie move their eyes while being dead.
When Fulci emerges from the car with an ax behind him, he creeps over to the engaging prostitute but her mouth doesn't move.
When Fulci is chasing the homeless man with his car, the car's Florida license plates can be seen (despite the scene taking place near Rome).