When Hunt's Audi stops when the gun dealer's car leaves, the screw covers on the front license plate are black and white. When the same Audi stops after losing the other car following the chase, the screw covers are reversed (white and black).
The calendar in Alex's flat suggests that the events take place on and about 12 August 1981. One of the songs played in the club scene is "Don't You Want Me" by The Human League. This track was on the album Dare, which wasn't released until 20 October 1981. Originally considered by the band to be a "filler" track, it wasn't released as a single until 5 December 1981.
When where Alex takes Marcus back to his parents' house, when Alex gets out of the car a satellite television dish can clearly be seen on the house over the road. Satellite TV did not become commercially available in the UK until 1989. The dish itself appears to be a Sky Digital mini-dish, which only became available in 1998.
The events take place in July 1981. The song "Don't you want me" by Human League, playing in the bar Nirvana, wasn't released until November 1981.