An estate agent's sign displays a telephone number beginning with '028'. 028 only became the area code for all of Northern Ireland in the year 2000.
Early in the film, Gordon goes shopping with his family to the 'Raul Street' shopping center. An advertisement for a local restaurant shows prices for various dishes in Euros, which of course did not exist until 17 years later.
Some of the vehicle registration numbers shown were not released at the time the film was set. A Ford Fiesta shown has a registration number that was not released until at least twenty years later.