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.
Factual error: Gorillas are strict vegetarians. 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.
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.
Factual error: You see the serum flow toward the heart and then branch out through the rest of the body. The same thing happens when they try to do it with Kevin Bacon. In ANY normal circulatory system, blood that reaches the heart from the veins has to go straight to the lungs to be deoxygenated before it gets sent to the rest of the blood. The serum clearly doesn't do this - the only way that anything could skip the lungs so blatantly is if there was a hole in the heart.