The era of imperial expansion characterized by "claiming" countries by metaphorically planting a flag preceded both World Wars, and the countries involved often regained independence.
In one long shot of some houses small black Sky TV satellite dishes are visible. Sky TV did not begin broadcasting until the late 1980s, and this style of satellite dish was not rolled out until the launch of Sky Digital in the late 1990s.
The learner car that Combo drives has a 2005 tax disc displayed on the windscreen.
The track "Since Yesterday" by Strawberry Switchblade can be heard on the radio although the song was not released until November 1984.
Modern day lamp post visible in the streets.
The takeaway that Shaun passes, early on in the film, has a telephone number starting with area code 0115 - this area code did not come into effect until 16th April 1995.
When Combo was explaining the level of unemployment in the UK at the time (1983), he referred to a figure of 3½ million. Although unemployment figures in the early 1980s were staggering this figure was not reached until 1986.
When Shaun first meets with Woody, Milky and the other skinheads, in the tunnel after the fight at Shaun's school, you can clearly see that they've written 'Screwdriver' with spray-paint, but the group it refers to is spelt 'Skrewdriver'.
Shaun's Family has a blind spot about the Stranger Danger PSAs which were popular in the 70s and repeated in the 80s.