A sharp-eyed executive producer of The Simpsons spotted a subtle mistake that seems to have gone unnoticed for more than two decades. In his tweet, Matt Selman points out that a photo of Maggie is hanging on the wall in an episode that takes place before she was born. In fact, the season-six episode ("And Maggie Makes Three") is all about Marge's pregnancy with Maggie and Homer's initial reluctance to become a father of three. (Forward to the one-minute mark of this video.)
Couldn't it be a photo of Lisa? Nope. In addition to Selman's confirmation, BuzzFeed points out that Lisa always wears a white necklace in her baby scenes. The episode ends with Homer's change of heart, demonstrated in "one of the most moving scenes in the show's history," per BuzzFeed, which lays it out in photos. (The show recently confirmed a Michael Jackson rumor.)