Other mistake: Towards the end of the film, as the two kids are escaping through the subway being guided through the night vision scope used by the army major, they are virtually blind and have to pick their way through dead bodies, escalators etc. This seems a bit unnecessary as the M4 rifle to which the night vision scope is attached also has a torch attached to the RIS rail. Military spec torches are extremely bright - why not just turn it on? They can't be worried about being spotted, because they are shouting at each other, not concerned with what might spot them.
28 Weeks Later (2007)
1 other mistake - chronological order
Directed by: Juan Carlos Fresnadillo
Starring: Rose Byrne, Robert Carlyle, Jeremy Renner, Harold Perrineau
Visible crew/equipment: In the scene where Doyle is talking to the helicopter pilot at the park, you can see another pilot on the left side of Doyle's head for a split second. (01:14:50)
Question: In the first movie the infected only stayed in the shadows and came out at night. How come the infected in this movie are running around in broad daylight?
Answer: Nobody ever said they could only come out at night. As their food became scarce, they'd taken to daylight hunting as well.
Captain Defenestrator