'The Simpsons' marathon: 6 things to notice while watching FXX's 12-day run

'The Simpsons' hits FXX for a 12-day marathon slated to play every episode ever created. (Photo via Fox)

LOS ANGELES (Variety.com) - Five hundred and twenty-two episodes of "The Simpsons" shown over 278 continuous hours? Don't have a cow, man!

When 21st Century Fox's general-entertainment outlet FXX unspools every "Simpsons" half-hour ever made (plus the 2007 movie) starting at 10 a.m. Thursday, it would seem to offer an overwhelming task: How can a viewer immerse himself or herself in such a torrent of content and yet pause to note some of the nuances in the stream?

Your answer is here. While bingeing on Bart, Lisa and Maggie in such amounts could make the average couch potato feel as if they've been drizzled in butter, cheese and bacon, the simple fact is the series has its Easter eggs and special moments that everyone should at least try to note. Below, a small sampling:

Odd Musical Notes: Sure, Coldplay (Season 21, Episode 11) and U2 (Season 9, Episode 22) have made cameos on the series, but so too have some obscure and surprising players. Keep a lookout for NRBQ (Season 11, Episode 8); Bachman Turner Overdrive (Season 11, Episode 13); Sonic Youth (Season 7, Episode 24); Spinal Tap (Season 3, Episode 22); Robert Goulet (Season 5, Episode 10); and Phish (Season 13, Episode 16).

A Strange Alias: Who is John Jay Smith? Due to contractual obligations at the time, the show could not tell viewers of the first episode of the series' third season ("Stark Raving Dad") that Michael Jackson supplied his own voice to a character who believed he was, in fact, the singer. The solution was to identify the musician as John Jay Smith - a ploy that hardly convinced anyone that Jackson wasn't really at work behind the scenes.

Boy, That Voice Sounds Familiar: Actor Phil Hartman, best known for his years on "Saturday Night Live," provided the voices of various characters in more than 50 episodes of the series. Whenever shady lawyer Lionel Hutz or ubiquitous B-movie actor Troy McClure appear on screen, it's Hartman who brings them to life. 

O'Brien Abounds: Late-night host Conan O'Brien wrote for "The Simpsons" for a while, and he also appeared in the show. You can spot the lanky red-headed comic in Season 5's "Bart Gets Famous." But you can also enjoy his wit during the classic fourth-season episode "Marge Vs. the Monorail," which he wrote. 

How Old Is Mr. Burns - Really?: The question about "The Simpsons'" perpetual crank often emerges, particularly because the character himself has acknowledged being born in the 1800s and information surfaces in the series that his mother had an affair with President Taft. Viewers can get a glimpse of his storied history by looking for a framed pictures of ol' Monty and Elvis Presley in the fourth-season episode "Marge Gets a Job."

'The Simpsons' and Social Media: When Homer, Marge and family first arrived on TV in 1987 (during vignettes on Fox's "The Tracey Ullman Show") the World Wide Web was barely in swing, let alone social media and streaming video. But FXX will try to use this cartoon clan to spark social-media buzz by having "Simpsons" executive producer and showrunner Al Jean tweet along with other series writers throughout the marathon (but not continuously). Look for their words and remarks at Twitter handle @everysimpsons and official hashtag #EverySimpsonsEver.