Factual error: When the two kids are going back to their old house, they take a moped from an old pizza shop. The registration plate on said moped is 'KW54 JKO'. This would indicate that the moped was produced after September 2004, two years after the first outbreak. (00:31:20)
Factual error: There is a point where the children travel to their home to get some things. They travel to SOUTH London but as they near their home, look at Canary Wharf in the background! The positioning of the buildings show they are in the EAST towards Dagenham area.
Factual error: The aeroplane lands at London City Airport, although the passengers enter Stansted Airport.
Factual error: There is a point when the boy and girl are travelling to Canary Wharf. A couple of shots before they arrive there, you see the DLR train approach a bend (There is a white building to the left). This is approaching "South Quay Plaza" station. This station is two stations past Canary Wharf.
Factual error: When Scarlet, Tammy and Andy enter the train station, there is a poster for Oyster Cards, which didn't get introduced until July 2003. This film is set 28 weeks after the occurence in 2002. There would be no need to update the train system, as London would have been in turmoil.
Factual error: This film takes place 24 weeks after the film "28 Days Later", which is approximately 6 months later. Yet in both films it's the middle of Summer.
Factual error: The route the children take to their house on the moped doesn't make sense - this is just to show the London landmarks.
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