Deliberate mistake: When Dave is in the pod arguing with Hal to let him back in, various patterns of light are projected on Dave's face presumably from the video screens that say NAV and COM and such. Light on such a screen would diffuse and not project like this. It is likely those screens had rear projection and they merely removed the screens for this effect.
Deliberate mistake: When Ben is discussing boarding up the windows to Tom, he says he still needs to get a few spots upstairs. Why would he need to board up the upstairs windows when the zombies have no way of reaching them?