When Pinhead is in the church, he stands behind the table, and the candle to the right of him is straight. He then pushes the cross off the front, look at the candle, it is now on a slant then in a split second the candle is straight again as if it had never been touched.
At the end of the film Pinhead tricks Joey into giving him the puzzle box by posing as her dead father. As soon as she hands the box over he takes a knife from his belt with his left hand and poises to strike. Then it cuts to a shot from behind and he's now gripping the knife with his right hand.
In the scene where Joey is playing through the video from the asylum, the video suddenly cuts to a man who tells her that the woman subject in the video is telling the truth. She rewinds the tape, but the screen is now blank. However, the reflection of her glasses clearly show that there is still a man on the screen.
When Pinhead arrived to the church, he made a metal cross of some kind melt over the hands of the priest. But when he gave the same priest a piece of his body to eat, the clergyman clearly have both hands in perfect shape, free from any melted metal.
When Pinhead is just about to start killing everyone in The Boiler Room night club, a man catches the first hooked chain that Pinhead unleashes. Yet when you look closely as you see the man holding the chain there is no hook, but a piece of wire.
When Terri tries to leave the hospital, Joey stops her and asks her about the boy with the chains attached to him. Terri is standing right in front of a pair of double doors while she is speaking. Joey is then distracted and hurries back to the room with the injured boy, and in the background we see Terri hesitate for a second, before starting to back up and go slightly through the double doors. But when the camera then does a close up on Terri, she is still standing hesitating in front of the doors and is a little further forward than she was before. She then backs up and exits through the doors again.
Joey finds Doc has been decapitated in the club yet his head is intact when he comes after Joey as the Camerahead Cenobite. When Joey sees him without his head, he was in the process of being made into a cenobite.
When Joey is sitting down inside the bus, she is resting her head on a window. We hear a bang on this window, and Joey she is startled. The camera shows us a haggard man banging and groaning for about 2 seconds in frame, yet this is impossible as the bus Is moving the entire time. The man would have to be an extremely fast runner to do what he is doing, all the while remaining in constant speed with the bus.
None of the Boiler Room patrons make it out of the club alive & Joey has to step through all the bodies before she meets Pinhead but she has no problem getting past all the corpses & onto the street without him stopping her.
The goof item below may give away important plot points.
The scene in which the Sandy is absorbed by the pillar: when the sculpted face of Pinhead opens its eyes and starts screaming, Sandy's face is only about one foot away from him. Seconds later, during the shot in which she is torn apart, this distance has increased considerably, for no apparent reason.