While The Simpsons' quality has certainly fluctuated wildly over the course of its 33 seasons to date, there's no arguing with the depth and volume of its characters and lore, such that even the most die-hard Simpsons fan surely can't keep track of everything.
As with most long-running animated series, The Simpsons' writers have maintained a sensibly fluid and elastic approach to their ongoing continuity, whereby what happens in one episode won't necessarily be picked up in the next.
But at the same time, sometimes an episode makes a declaration or implication so fascinating that its absence in future episodes is totally, bafflingly bizarre.
That's definitely the case with these game-changing details made clear in just a handful of The Simpsons' 700+ episodes, yet otherwise heavily downplayed if not ignored outright.
Again, the show's ambiguous sense of continuity generally means that conventional plot holes aren't really a thing, but it's nevertheless rather odd that these startling revelations and unforgettable details were largely just dropped and then quietly ignored.
But many fans never forgot, and will routinely bring these details up at every possible opportunity...
10. The Simpsons' Home Has A Rarely-Seen Rumpus Room
As much as even a casual Simpsons fan likely assumes they know the Simpsons' home like the back of their hand, it's easy to forget that there's an extra room in the house we rarely catch a glimpse of.
Behind the garage and next to the kitchen is a "rumpus room" - a recreation room, basically. It was first seen in the season two episode "Itchy & Scratchy & Marge," and has appeared in a grand total of just eight of The Simpsons' episodes to date.
The room's shockingly meagre showing throughout the show was eventually mocked in the season 25 episode "White Christmas Blues," where Marge tells Homer, "Well, there's a rec room off the kitchen, but sometimes it's there and sometimes it isn't. Our house is very odd that way."
Nobody involved with the show has offered up notable comment on the room or why it's been so fleetingly included throughout the series, which only makes its existence that much weirder.