One persistent fan theory states that Disenchantment actually exists in between the present day of The Simpsons and the future of Futurama, thanks to a brief gag in the latter’s pilot episode. As Fry (Billy West) is cryogenically frozen, viewers see the world outside his window crumbling and being rebuilt several times. During one of these apocalypses, medieval-looking castles pop up, only to be destroyed again by aliens.

Another blink-and-you’ll-miss-it Easter egg of Fry, Bender, and the Professor briefly appearing in a time machine – in the first season finale of Disenchantment, “Dreamland Falls” – seemed to confirm the connection between the two shows, while still leaving the timeframe muddled.

“I Know What You Did Next Xmas” has finally cleared the waters. As the Professor is traveling backwards from the future – something he goes out of his way to say out loud, just so there’s no confusion – we see him pass by Disenchantment’s Bean, Luci (Eric André), and Elfo (Nat Faxon), confirming that Disenchantment is, in fact, in Futurama’s future.

The connection of Futurama and Disenchantment to The Simpsons is a tad murkier, or at least full of contradictions. (Which is saying something, given that none of the Simpsons have aged in thirty years.) You see, in the first seasons of Futurama, The Simpsons was very clearly a television show and pop-culture phenomenon. A pile of discarded Bart dolls are featured in “A Big Piece of Garbage,” while “Mars University” shows Bart and Homer dolls as carnival prizes in the background. “Leela’s Homeworld” includes Bart’s Macy’s Thanksgiving Day balloon. Later, in “Lrrreconcilable Ndndifferences,” Bender even asks the jarred head of Matt Groening when a second Simpsons movie is coming out.

But then came “Simpsorama.” The 2014 The Simpsons episode was a full-on crossover with Futurama, shortly after the latter’s second (third?) cancellation.

“Simpsorama” finds Futurama’s future overrun with mutant bunnies – themselves a callback to Groening’s Life in Hell comic – the direct result of some B-movie-style science involving Bart’s snot, Milhouse’s lucky rabbit’s foot, and just a bunch of nuclear waste. Tracing the DNA to Homer (Dan Castellaneta), Bender (John DiMaggio) travels back in time to eliminate the problem, but befriends Homer instead, leading Fry, Leela (Katey Sagal), and Professor Farnsworth to try their hand at Terminatoring him up instead.