Titus Andronicus (theatre)/WMG

The Movie takes place on a world in the Warhammer40,000 galaxy.
As well as explaining the Anachronism Stew, the pseudo-Roman culture and blue-armoured soldiers on motorcycles must have definitely been inspired by the Ultramarines, who visited the planet sometime in the past. (the Imperium may have lost track of the planet since then) And someone in the cast is definitely channelling some Chaos into the royal palace, probably Slaanesh.
 * You have no idea how relieved I am that I'm not the only one who thought of this.

The Movie takes place in the kid's head.
He's obviously hyped up on sugar and is having a mental breakdown.