After Wikus is ejected from the damaged Exo-suit, the exo-suit disappears completely from all subsequent shots, including the aerial shot of Koobus's death.
When Wikus is in the sub-level MNU HQ firing range, and when they are fitting his HUMAN (right) hand to the AMR-B21 directed energy weapon, the thumb and index fingers have intact thumb and finger nails. In the office space after returning from field operatioms, Wikus picks at his right hand index finger and the nail falls off. He then visits the restroom where his thumbnail is pulled free when he tugs on [it] with his teeth. Both expose a red "quick". Then as mentioned above, the nails are perfectly manicured in the MNU HQ basement firing range.
When Wikus looks at his chest, he observes the black boils which are forming; however, in a later scene, when he is caught temporarily by the soldiers, he has a clean chest (except for the blood from other bodies on him).
After Wikus is ejected from the badly damaged Mecha suit, he lands on a flat dirt area with litter all around him and starts to crawl slowly. When the camera comes back to him, he's crawling through dried up brush and there is a fire near him. When the screen reads "74 hours after exposure," he is again crawling on a dirt path with no vegetation or fire around him.
In the scenes following the escape from the MNU facility, the team hunting Wikus is shown from an AgustaWestland Merlin helicopter. In the next scenes, the helicopter is an Aerospatiale Gazelle. The cabin shots are clearly from a Gazelle judging from the size of the interior.
When Wikus is first admitted to hospital and is having his arm checked, it is quite clear that he has a hairy chest under his vest. Afterwards, he is seen with his shirt off and is hairless. Because the surgeons are planning on opening his chest to remove his heart, it is likely that his chest was shaved in preparation for the procedure. Another reason may be, due to the changes his body is undertaking (fingernails falling off, etc.), his hair may have fallen out.
Everyone has modern mobile phones because the movie is not actually set in the 1980s. It's the date of the aliens' arrival. The events of the film are approximately 20+ years later, and on-screen date stamps put the movie explicitly in the year 2010.
Anthony Fridjhon, who plays "MNU Executive," appears twice in the cast list for the same role.
MNU, a supposedly highly secure corporation, neglects to remove Wikus' security clearance, allowing him to reenter MNU and access highly secure areas using his fingerprints.
When the mothership activates, the Mecha suit performs an automatic defense program to protect Wikus who is now shown as a "Prawn"; however, when Christopher is also under attack just a few moments later, the suit does nothing.
If the fluid is all they need to escape, why not use the fluid from the robot? It is controlled by electronics. We can even see the fluid dripping from the robot when it is destroyed. Even if they haven't any robots left but the one at the Nigerians, killing the Nigerians would be much easier than breaking in at the MNU.
When the MNU workers first walk up to Christopher Johnson's shack in order to evict him, the radio operator identifies the shack as "Yankee Foxtrot Five Three Zero," or YF530; however, the number on the shack itself is FY530.
When Wikus is having his bandage removed at the hospital, the doctor is not wearing rubber gloves. Any medical professional would be gloved (and probably masked) when cutting off a bloody bandage.
As the interviewed people are talking, their titles and names were placed on the screen. When one of the MNU officers is talking, the word LIAISON is misspelled "LIASON".
On the DVD extra documentary about alien reproduction, the lecturer refers to "seminal vesticles". It should be "vesicles".
Early in the film there are shots of "aliens not welcome here" signs around the city. One sign begins "These public premises an the amenities thereof..." - the "d" on "and" is missing.