Joker: Every Easter Egg & Reference We Spotted

22. Arkham Asylum

Arkham Asylum is one of the most iconic locations in Batman lore, typically housing many of the Caped Crusader's most dangerous - and mentally ill - enemies.

But with Joker's general attempt to present a more pared-down vision of this world, Arkham Asylum is actually renamed Arkham State Hospital, and aside from being name-dropped several times throughout the film, Arthur even briefly visits the building in order to retrieve vital information about her past.

This is clearly following the lead of Frank Miller's 1986 comic The Dark Knight Returns, which similarly renamed Arkham Asylum to Arkham Home for the Emotionally Troubled, implying a decidedly less dramatic and more compassionate attitude towards the mentally ill.