It's not like the producers of The Simpsons are obsessed with continuity – in fact they play it rather fast and loose with the timeline on the show.
But, when executive producer Matt Selman spotted a pretty big continuity blunder on Wednesday, he thought it worth sharing on Twitter.
"Maggie is in photo on wall behind Marge telling Homer she’s pregnant with Maggie," Selman wrote alongside a screen shot from episode 13 of the sixth season of The Simpsons.
Fellow Simpsons writer Al Jean was quick to respond to Selman's observation.
Simpsons fans chimed in and discussed who they felt was to blame.
Jean joked that the continuity blunder had led to mass firings on the show.
Other fans came up with theories as to what might be the reason for the mysterious Maggie photo.
Other observant fans pointed out that the exact same thing had actually happened before on the show.
And of course, a fan had the perfect Simpsons reference for the moment.
But honestly, over the course of 30 seasons, there's bound to be a few slip ups.