Continuity mistake: After the sergeant has a parasite bug forced into her, she grabs a syringe kit left on the table by the medic. When she flips it open, there are 7 (maybe 8 at most) syringes in the kit (the last one is broken). A few moments later, private Sandee follows a trail of syringes left on the ground to the sergeant. There are at least 7 syringes on the ground, and 3 others in the sergeant's thigh.
Factual error: During the mess hall fight between the Sergeant and Horton, the Sergeant cuts the private's head with a cleaver and raises it "to show us". Horton's head is heard breathing and the breathing sounds react to the bug coming out of the head's mouth. I know the parasite bug makes the host's body quite resilient, but wouldn't the head still needs lungs to produce breathing sounds of that kind?
Continuity mistake: When the sergeant crushes the bug with her rifle's butt in the incinerator, we can read "The bug stops [...]" on the side of the stock and the butt is flag. In the next shot where she unfolds Dax, the text is gone and the butt has a clear bump at the bottom.
Revealing mistake: When they fix the door, in the last few frames we see while the door is still moving up, the gear stops spinning in the "rail".
Continuity mistake: When they fix the door, while the door is moving up, we see three cables going over the door's track and strapped somewhat together. On the next shot, while the door is moving down, there are only 2 cables visible and they are positioned in a different way. It is also worth noting that earlier in the movie, when they try to close the door for the first time, the three cables are positioned in a totally different way.
Continuity mistake: Right after the first encounter with Dax (who is locked in the incinerator), when the soldier comes to warn them of a new bug attack, the chin strap that is hanging from the Sergeant's helmet switches sides.
Continuity mistake: When the troopers repair the tesla fence you can see that when the bug is caught between them they are very close together, yet in a later overhead shot of the outpost the posts are seen to be very spread out.
Audio problem: At the end, as Dax rescues Sahara and loads her into the evac shuttle, he steps away from the craft. Bugs are swarming the scene, but it is apparent that Dax is staying behind. Sahara cries out, "You stay here, you die!" and we hear Dax reply, "Murderers don't go home," which is an overdub. His mouth visibly says something very different with several more syllables.Charles Austin Miller
Continuity mistake: When Billy, Dax and Sahara repair the tesla fence, Dax hands Billy his knife, telling him to cut the cables and splice them together. Billy cuts into the cable using the tip of the blade and he is thrown backwards. Seconds later, when he looks at the smouldering knife, there is a big dent in the knife near the handle. This mark should be at the tip of the blade instead of being near the handle.