In the scene where Billy's brother argues with a miner in the local shop, there is a plastic Polo dispenser that wasn't around in 1984.
At one stage in the movie, Billy and his dance teacher travel across the Transporter Bridge, the only working cradle bridge in the world, which crosses the River Tees from Middlesbrough to Port Clarence, Stockton-on-Tees. At the time of the Miners Strike in 1984, when the film is set, neither Middlesbrough nor Stockton-on-Tees had an active coal field. Whilst the Transporter Bridge, now a grade 2 listed structure, is still working, it is not really a reguarly used entry or exit use from Teeside, if Billy and his teacher were going to an audition. Which raises the question as to why they were on the bridge, apart from giving the director the chance to show off a spectacular structure.