Warner Bros. upcoming DC film Joker contains at least one reference to the DCEU, and more specifically Batman v Superman. Under the direction of Todd Phillips, Joker sees Joaquin Phoenix tackle the role of the mentally unstable Arthur Fleck, who over the course of the film becomes Gotham City's Clown Prince of Crime known as The Joker. The film recently premiered at the Venice Film Festival, with Phoenix's performance already receiving Oscar buzz.

The film also serves as a testing ground of sorts, not only from controversies relating to Joker's script, but also given that it is not connected to the ongoing DCEU. Indeed, Bruce Wayne will only appear in the movie as a child, while Joker will have an R-rating upon its October release. However, despite it being disconnected from the DCEU, its newly released second trailer contains at least one Easter Egg to the franchise.

Related: Why Joker Is Facing Backlash Despite The Great Reviews

A user on the DC_Cinematic Reddit recently shared a still from the new trailer alongside a shot from the opening scene of Batman v Superman. With both scenes set outside of a movie theater, the user zeroed in on a shared characteristic of both - specifically, that a poster for the 1981 film Excalibur can be seen in the background of each.

Joker Movie Excalibur

The Excalibur poster seen in Batman v Superman appears during a defining moment in the life of the young Bruce Wayne. Namely, the murder of his parents, Thomas and Martha, an event which sets him on his path to eventually become The Caped Crusader. The real question, however, is does the shared inclusion of an Excalibur poster point to some more definitive link between Joker and Batman v Superman?

What's curious about this discovery is the fact that director Todd Phillips has stated that Joker is not a direct DC comics adaptation. The film reportedly used Martin Scorsese's Taxi Driver and King of Comedy as its template of a man slowly descending into madness. Making the DCEU Easter Egg even more intriguing is producer Emma Tillinger Koskoff's own apathy towards comic book movies. Together, these could point to there being more to the Excalibur poster than meets the eye.

While Jared Leto has already portrayed the DCEU's Joker in 2016's Suicide Squad, Phillips may be creating some stealth connectivity with the DCEU. For one thing, the early 80's setting of Joker lines up surprisingly well with the opening of Batman v Superman. Additionally, the men in clown masks seen here clearly point to Fleck's Joker becoming a low-level Gotham City crime boss over the course of the film. With the subtle hint of connectivity between Joker and Batman v Superman, the film may use this as a means to position Phoenix's Fleck as a kind of proto-Joker, upon whom Leto's Joker eventually predicates his own criminal identity.

Related: Joker Stole Another Comedian's Joke For His Stand-Up

Of course, it's just as likely that Phillips and Warner Bros. are being honest that Joker is genuinely untethered to the DCEU continuity, and the director is just having some fun plugging a Batman v Superman Easter Egg into his Batman-less Joker movie. To be sure, creating such a clandestine link between Joker and the DCEU would be quite an about-face after positioning the film as the opening salvo of an Elseworlds brand of DC films. Nevertheless, with Phoenix's performance generating widespread acclaim well before the film's wide release, there's plenty for fans to theorize upon over what, if anything, the Excalibur poster could mean, along with the place of Joker in DC's cinematic canon.

Next: Joker Theory: Joaquin Phoenix's Joker Creates Batman

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