Plot hole: Because humans have a layer of subcutaneous fat under the skin, the bug that travels under Harry's skin would have caused not only significant damage but an amazing amount of pain while moving around. There would have also been severe internal damage caused by the bug if it traveled into his colon where they ended up removing it from.
Character mistake: In the scene where the gorilla type creature has taken out one of the security cameras, they say "one of the creatures just destroyed video four" but if you look, camera four is intact and it is camera two that has been taken out. (01:08:05)
Suggested correction: Monitor names and video names are not the same so monitor 2 which is out, could in fact be displaying images from video 4. On a multi monitor system, there could be tons of video feeds that could be played through those monitors.