During the helicopter/freeway sequence, the same clown-faced ice cream truck gets blown up twice.
There is no hole visible in Darkman's hand after he rips it through the bolt pinning it to the girder. This can be clearly seen when he swings to save Julie right afterwards.
When Julie follows Darkman back to the warehouse, his skin has melted, but when he is crying behind the cabinets, his fake hands are still there.
During the final confrontation scene at the construction site it is night and dark outside. In the next shot when Peyton and Julie leave the construction site it is bright day.
While holding on to the helicopter, Darkman grabs the hook and rope and lets it dangle. The rope then disappears and reappears between cuts.
Throughout the movie, Darkman is able to talk as normal despite his lack of lips. You cannot pronounce 'b', 'f', 'm', 'p', 'v' without lips.
When Julie is handcuffed and falls off the building, she gets caught on the re-bar in a way that would be impossible for how she fell.
Westlake is viewing the synthetic skin cells with a light microscope, so when the power goes out in the lab the cells would no longer have been visible. Even if the laboratory lights were off to begin with, the cells would have failed to remain stable due to the fact that the microscope operates by the refraction of light through the sample.
Peyton does not use the correct type of microscope to look at the piece of nose skin. To see the cell as he did, a slide of the skin would have had to be prepared and viewed under a transmission electron microscope, and he appears to use a compound light microscope.
When the henchman is firing rivets at Darkman in the uncompleted building, rivets weren't being used to make connection between girders.
Virtually all used bolts and nuts to make such connections.
When Peyton breaks the finger of the fairground worker, the close-up clearly shows it to be made of rubber.
During the warehouse shoot-out, an obvious dummy lands on the hood of a car, then falls off and lands on some boxes.
Much of the helicopter chase scene is flipped horizontally.
When being punched and hanging onto the helicopter, Darkman makes grunts that suggest he's feeling the pain from the punches.
When Darkman is hanging under the helicopter and is flying just above the street, the camera pans left and you can see the shadow of the crane on which he is hanging.
When Darkman runs up the stairs over the bridge on the roof you see a few crew-members on the roof.
During the warehouse fight at the beginning, a ramp used to flip one of the cars is clearly visible before the camera pans left as it goes over.
The camera crew is reflected in one of the goons' cars as they pull up to the storage pier.
When Rick wanders down an alleyway, just before he's captured by Darkman - the camera's shadow passes over an apple box.
Westlake's ability to imitate voices makes no sense, not so much that he doesn't have skin to be able to do it, it's that he just can.
There is absolutely no scientific evidence to support the doctor's assertions that someone devoid of pain sensations would go insane as a result - people suffering from leprosy commonly lose the ability to feel pain or other touch sensations as their nerves deteriorate but this does not in itself cause any psychological damage.
The synthetic skin cells are stated to have a membrane potential of 122 megavolts. Human cell membrane potential is measured in millivolts, making this off by a factor of a billion.
During the scene in the lab when Peyton and his assistant discover that the synthetic skin is photosensitive, they alternate using the microscope though neither of them re-focuses the lenses. No two people have exactly the same eyesight and given the magnification used, they would almost certainly have to adjust the lenses for their own eyes after they use it. Yakitito also keeps his glasses on while looking at the microscope but this could be down to his excitement at the discovery.
The spinothalamic tract is stated to transmit pain and vibration. It actually transmits pain and temperature.
Durant trims his cigar too much. If you trim away the entire cap like that, the wrapper will start to unravel.