The Simpsons is quite possibly the greatest animation of all time, but even Matt Groening's tour de force isn't immune to its fair share of writing blunders.
While the show is still gracing our screens three decades on from the pilot, one observant viewer spotted a glaring error in the sixth episode of the third season called And Maggie Makes Three, which aired in 1995.
The episode sees lovable, overweight family man Homer Simpson and his endearing wife Marge tell Bart and Lisa how their little sister Maggie was born and explain why there are no photos of the sweet baby in their family albums.
However, when Marge is in labor, a photo of Maggie appears on the wall behind the pair as they recite the story.
In fairness, The Simpsons executive producer Matt Selman owned up to the mistake, tweeting a screengrab of the error and writing: "Maggie is in photo on wall behind Marge telling Homer she's pregnant with Maggie."
Writer Al Jean wrote: "Canon is in ruins!"
Yeardley Smith, the voice of the precocious eight-year-old Lisa Simpson, tweeted: "Oooops."
However, that's not the only blunder ardent fans have noticed.
In a scene which sees Homer run away screaming when Marge tells him she's pregnant with Bart, Homer freaks out and runs past a picture of Bart's younger sister Lisa.
Have you noticed any blunders from the series that might not have been picked up on yet?
If so, be sure to let us know in the comments below!