Sam orders himself to 'follow the yellow brick road'
Gene Hunt has a poster of the film up in his office.
When Sam asks Annie "Are you a doctor?", she replies "I'm about as qualified as Dr Kildare."
Gene asks Sam "Where are you today? Here or planet of the Clangers?"
Sam stares at a billboard and stumbles around town exactly like Marty McFly
DCI Gene Hunt, appearing as Jackanory on DI Drake's television, says "SHUT YOUR GOB! Or I'll come 'round your houses and stamp on all your toys." This is the threat DCI Hunt uses in the premiere Life on Mars episode, to convince a bunch of local kids to keep an eye on his prize motorcar.