By now, lots of the world will have seen Todd Phillips' Joker. Lots of those people will now be very much certain that they've just seen the Best Actor award winner at next year's Oscars. Some might not be quite as enthusiastic, but it was always going to be divisive.
The strange thing about this wonderfully intense, viscerally affecting movie - which is far smarter than some are giving it credit for in the wake of some of Phillips' comments - is that it was presented as a stand-alone movie, but it is far from it. Not in terms of it knowing its cultural reference points at the very least.
The film is very obviously a love letter to Martin Scorsese, so the visual references and the narrative links to The King Of Comedy and Taxi Driver are not so much Easter Eggs as they are integral story elements. But beyond them, there are references to the comics (despite assurances to the alternative) and to other films, but they're often lost to the background because of the power of Joaquin Phoenix's performance.
When Arthur sets his mind on being a professional stand-up comedian, he effectively stakes out a comedy club, writing notes on how to be a comedian and laughing along with the jokes. Or pretending to and missing the beats of every joke, creepily.
The Easter Egg in question here is the club itself, which owes some of its history - its name, specifically - to one of the most notorious killer clowns of all time. The club is called Pogo's, which happens to also be the performing name of John Wayne Gacy, the killer clown who tortured and murdered at least 33 teenage boys and young men between 1972 and 1978 in Cook County, Illinois.
You have to assume that Gacy didn't exist in this world, because naming a comedy club after him would be pretty perverse, but it works for Joker.