Factual error: Gorillas are almost exclusively herbivores. They have been observed eating small insects and grubs but nothing larger. So why does Isabelle eat a rat at the beginning of the film? The serum may have turned her into a crazed killer, as it does with Sebastian, but it hasn't changed the structure of her teeth and palate, biochemistry of her digestive system and so on, all of which would be required. She might kill or torture the rat, but she'd never eat it.
Plot hole: There must be a lot of dumb scientists in Sebastian's lab. While defibrillating the invisible gorilla, (s)he becomes completely visible for a moment. However, not once do the scientists consider that applying a mild electrical shock to the system renders the invisible animal visible again - that electricity may be the key to the whole invisibility problem. They don't even comment upon the fact that the gorilla does become visible.
Plot hole: Why on earth would the military be interested in a soldier (sailor, aviator, whatever) who has to go into combat naked and unarmed, and who is detectable by an enemy equipped with a pair of cheap, mass-produced goggles? How would you treat them if they were injured? They would be utterly useless in any form of military operation, even espionage.
Factual error: When the crew pour liquid latex over Sebastian's head and neck, in order to create a fairly life-like mask of his face, it simply pours over his head as though he is completely bald, and he is able to remove it later by pulling it off, exactly like a glove. However, the film creators seem to forget that Sebastian has quite a thick head of hair, and technically, when they pour the latex over his head, it should stick and/or pour along the outline of his hair. Whilst drying, the mask should equally have stuck to his hair and become very difficult to remove, and yet as they create the mask, no hair appears to exist on Sebastian's head. They did not shave Sebastian's head - later in the film he falls into a swimming pool and we see a clear outline of his entire body, with a full head of hair. (00:47:15 - 00:48:30)Tom
Factual error: When they inject the serum that counters the invisibility into the gorilla, you see the serum flow backwards toward the gorilla's hand. Veins have special valves that prevent blood flow from going backwards and to force blood to go to the heart, so how the serum manages this is beyond me.
Factual error: When they make the gorilla visible again, her heart becomes audible at the same time it becomes visible. This happens with Kevin Bacon as well. But that shouldn't happen, because it was just invisible, not inaudible. And it wouldn't make a noise like that unless you were listening through a stethoscope.