The Simpsons: 20 Annoying Mistakes You Didn't Notice

15. Carl Carlson's Heritage

Another backstory/origin tale issue, no doubt created by the sheer number of episiodes, and writers' commitment to adding new joke elements to established characters. Carl Carlson has both a black family and a white family according to the show. In "The Seemingly Never-Ending Story" and "The Blue and the Gray", we meet his dad and sister, who are both black and resemble Carl closely, but in "The Saga of Carl", Carl reveals that he was adopted by a white family (possibly in Iceland, since he reveals he spent some of his boyhood in Iceland in "'Scuse Me While I Miss the Sky," so quite who those two suspiciously familiar looking charlatans remains to be seen.

14. Left-Handedness Is Apparently Temporary

The whole foundation for Ned Flanders' Leftorium is that there are many prominent lefties throughout Springfield, including billionaire Mr Burns, quite helpfully, which is ultimately what saves the store from closing when Ned is threatened with bankruptcy in "When Flanders Failed." That reprieve must have only been temporary however, since Ned himself has been seen doing right-handed things himself (which perhaps explains why he gives a right-handed salute outside his own left-handed shop) and most of the lefties who save his shop - including Bart Simpson, Principal Skinner, Moe and Mr. Burns - have all seemingly forgotten they were ever left-handed and limited by the unavailability of left-handed items.

13. How Old Is Wiggum?

Thanks to some more wayward writing, it has been established that Chief Clancy Wiggum is at least three different ages - or that he should be, anyway. In the timeline established by "Mother Simpson," Wiggum appears as a teenager - probably 16 - in a flashback to 1969, which would have made him 42 in the present (it was aired in 1995, but it doesn't seem that anyone else ages, so he could well still be 42). But then in "Weekend at Burnsie's" he appears to be a similar age, though he is markedly slimmer, and in the ironically named "The Way We Weren't" he appears in a flashback set when Homer was 10, confusing his age further, especially in line with his appearance playing cops and robbers with Homer when the pair are both children.