Simpsons World: The Ultimate Episode Guide, Seasons 1-20 is a book which combines The Simpsons: A Complete Guide to Our Favorite Family, The Simpsons Forever! A Complete Guide to Our Favorite Family Continued, The Simpsons Beyond Forever! A Complete Guide to Our Favorite Family... Still Continued, and The Simpsons: One Step Beyond Forever. It also includes seasons 15 through 20, and expanded all the episodes to at least two pages (episodes with more than one story, such as Treehouse of Horror, have four pages).
There are also appendices listing all the songs, every time Homer says "D'oh!" and "Mmm...", all of the Itchy & Scratchy Show episodes (including unnamed episodes), the differences between the various opening sequences, a full listing of couch gags, who voices what character, a full listing of First Church of Springfield marquee gags, a full listing of Krusty the Clown merchandise, a full listing of Troy McClure media, and all the guest stars.
It's original price is $150.00 in the US, and £95 in the UK.
- The episode "My Big Fat Geek Wedding" didn't originally air on April 18, 2008. It originally aired on April 18, 2004.
- The "Who Does What Voice" section misses some infrequent regulars and omits many of the speaking roles.
- In the "Celebrity Guest Stars" section, under June Foray, it says that she guest starred in "Homer's Night Out", which is wrong; she guest starred in "Some Enchanted Evening".
- In the "Celebrity Guest Stars" section, under Jan Hooks, it doesn't include "I'm with Cupid", "Eight Misbehavin'" and "Take My Wife, Sleaze"; those episodes feature Jan Hooks as Manjula Nahasapeemapetilon.
- In the "Celebrity Guest Stars" section, under Robert Stack, it not only accidentally states him as a guest star for "The Fat and the Furriest", but also lists the season for that episode as "TBD" instead of Season 15. Also, Robert Stack never guest starred on The Simpsons.
- Ms. Mellon's name is correctly spelled for the "The Stuff You May Have Missed" section for "Marge vs. the Monorail", but is misspelled in the "Who Does What Voice" section for Marcia Wallace.
- In the "TV Moment" box for "Brother from Another Series", "Niles" is misspelled as "Miles".
- In the synopsis for "Sleeping with the Enemy", it forgot to mention that Jacqueline Bouvier was at Bart's party along with Homer, Patty, Selma, Grampa, Maggie, Martin Prince, Ralph Wiggum, and Milhouse (via speakerphone).
- The character profile for "Itchy & Scratchy: The Movie" was originally "1920s Itchy & Scratchy" in The Simpsons: A Complete Guide to Our Favorite Family, but was changed to just "Itchy & Scratchy" in Simpsons World. However, the character profile for "Another Simpsons Clip Show" shows the "current" version of the duo, but is named "Itchy and Scratchy".
- In the "The Stuff You May Have Missed" for Treehouse of Horror IV's "Terror at 5 1/2 Feet", it says that Üter Zörker is not mentioned by name. However, he is mentioned by name when Bart says "Well, now that we're friends, Üter, how about loosening these straps, huh?"
- The sidebar image for Don Brodka in "Marge Be Not Proud" is reversed, as seen by the "Security" patch on the wrong side of his shirt and his walkie-talkie on the wrong side.
- Paul McGuinness is not credited as a guest star for "Trash of the Titans". However, the individual band members of U2 are listed in that episode and U2 is listed in the "Celebrity Guest Stars" section.
- The original airing for "When You Dish Upon a Star" had ""Butt.com" is not my e-mail address" as the Chalkboard gag, not ""Butt.butt is not my e-mail address". The "Butt.butt" version appears in syndication because "Butt.com" was revealed to be an actual web address. Also, the address has quote marks that are missing.
First Church of Springfield Marquees Goofs
- Despite many of the early episodes using topics in quotes for the marquee, that is missing from all the marquees that should have them. Also, some of the entries have the preface "Today's Topic:" (or similar) that appears in-episode, but some marquees are missing that.
- The entry "Private Wedding, Please Worship Elsewhere" should not have a comma.
- The entry for "Simpsons Bible Stories" is missing: "Today's Topic: Christ Dyed Eggs For Your Sins"
- The entry "Jesus Hates You" is missing the preface, therefore the entire marquee being "Today's Topic: Jesus Hates You".
- The entry "Church Council Meeting; Topic: Religion" is missing the preface, therefore the entire marquee being "Today: Church Council Meeting; Topic: Religion".
- The entry "Heck House - Scaredy Cats Not Wanted" is not on the marquee, because Heck House is actually a neon sign that is on the roof of the church, and the marquee only displays a skull and crossbones, which then switches to "Scaredy Cats Not Wanted".
Itchy & Scratchy Filmography Goofs
- The cartoon "100-Yard Gash" has an incorrectly inserted hyphen. (originally from The Simpsons: A Complete Guide to Our Favorite Family)
- The cartoon "Kitty Kitty Bang Bang" is incorrectly noted without hyphens. (originally from The Simpsons: A Complete Guide to Our Favorite Family)
- The cartoon "Dazed and Contused" is incorrectly spelled as "Dazed and Confused" (changed contused to confused), missing part of the original pun. (originally from The Simpsons: A Complete Guide to Our Favorite Family).
- Under "Burning Down the Mouse", it says that Lisa remarks, "My purpose in life is to witness this moment", which was actually said by Bart. (originally from The Simpsons: A Complete Guide to Our Favorite Family)
- The cartoon "Aaahhh! Wilderness!" is incorrectly spelled as "Ahhh! Wilderness", using one "a" and four "h"s instead of three each. (originally from The Simpsons: A Complete Guide to Our Favorite Family)
- The cartoon "A Briss Before Dying" is misspelled as "A Bris Before Dying", using one "s" instead of two.