1. No; Marge did not (she was always referred to as "Mom" or "Mrs. Simpson", even in the credits)
2. Yes; the one that immediately comes to my mind is Elizabeth Taylor, who has been both herself and Maggie
Krusty Gets Kancelled; Lisa's First Word
3. Yes; Maggie is not in a number of episodes, including The Last Temptation of Homer, in which no pictures of her appear, either
4. Yes; for example, Milhouse has had two 10th birthday parties (Bart was not at the "first" one but
was at the "second" one), and there have been various "last days of school" (including one
that took place at a different school)
Homer Defined; Homie the Clown; Kamp Krusty; The Secret War of Lisa Simpson
5. It depends on how you define "celebrates". They show Homer on his birthday, but everybody
else has forgotten it.
(Homer's birthday is mentioned in The Springfield Files; Marge celebrates hers in Life
on the Fast Lane (Jacques to be Wild), Bart in Radio Bart, Lisa in Stark Raving Dad
and The Dad Who Knew Too Little,
and Maggie in Lady Bouvier's Lover and Moe Baby Blues)
6. Phil Hartman is not in this episode, not as Lionel Hutz or Troy McClure or anybody else
Sweet Seymour Skinner's Baadasssss Song
7. Treehouse of Horror VI; the four people listed were the four people on the street in the "live action" scene when Homer is walking before entering the Erotic Cakes shop (Who Shot Mr. Burns?, Part Two had a "With" credit, but not a "Featuring" one)
8. They are the only groups whose members are not also credited individually
(in the case of The Who, it may be because not all of the characters were voiced
by "themselves")
Who Shot Mr. Burns?, Part Two; A Tale of Two Springfields
9. Pamela Hayden and Tress MacNeille (Frank Welker received "Special Guest Voice" credits for Two
Dozen and One Greyhounds and The Canine Mutiny)
Radioactive Man; Bart After Dark
10. Liz Georges (Maggie in the first Simpsons
appearance, shown on the 138th Episode Spectacular)
Despite what earlier versions of this quiz said, and
what it says in pretty much every other site, Catherine O'Hara did not
voice Moe's waitress in Flaming Moe's; according to the DVD commentary,
Jo Ann Harris (the voice of Janey and other young girls besides Sherri and
Terri) did. (O'Hara may have actually recorded her lines, but it was felt
Harris's voice fit the part.)
11. When he broke his class fishtank with a yo-yo, the string of which was still tied to his finger when he
said it
Bart the Lover
12. H.M.S. Pinafore (despite what Bart called it, there is no "The" in the title)
Cape Feare
13. Bart put his red cap into the wash along with Homer's white shirts (turning the shirts pink, which Mr. Burns detected), and Bart took Homer's "sanity test" for him
14. Bartman
Three Men and a Comic Book
15. Steve Bennett
The Front
16. Turning a football into Homer, who then hits a goal post
"The Bart Zone" ("Bart's Nightmare") in Treehouse of Horror II
17. October 1, 2010
Lisa's Wedding
18. "The handle of the Big Dipper always points to the North Star" (actually, the two stars at the
other end point to the North Star)
Call of the Simpsons
19. The 75-cent piece
Mr. Lisa Goes to Washington
20. Lisa (as opposed to Elizabeth, for example), according to Homer's local government file
Mother Simpson
21. Just Maggie; Marge's first name is Marjorie
22. All three fathered children who were born on the same day
And Maggie Makes Three
23. Twice; the first time was Bart through his radio microphone, and the other was via Herb's baby translator
Radio Bart; Brother, Can You Spare Two Dimes?
24. Ayn Rand
A Streetcar Named Marge
25. Maggie went after Homer with a pencil after seeing Itchy attack Scratchy with a knife
Itchy & Scratchy & Marge
26. Selma; two minutes
Principal Charming
27. Libertarian Party Headquarters
When Flanders Failed
28. Bryn Mawr (pronounced "Brinn Marr")
Separate Vocations
29. Hands Off My Jerky, Turkey and Bright Lights, Beef Jerky
Brush With Greatness; A Star is Burns
30. Stop the Planet of the Apes, I Want to Get Off
A Fish Called Selma
31. Conan O'Brien, when Bart appears on his show
Bart Gets Famous
32. Lisa, when Marge tells her she can't open a Christmas present early like Bart can
Marge Be Not Proud
33. Homer - but not on the show; he says it in a guest appearenace on an episode of Duckman ("Haunted Society Plumbers")
34. Lisa, when Marge worries that Maggie hasn't spoken yet
Lisa's First Word
35. The Bumblebee Man, when reading the news in Kent Brockman's place
Bart Gets Famous
36. Stampy
Bart Gets an Elephant
37. Snowball I was a male (according to one of Lisa's poems); Snowball II is a female (Lisa refers to the cat
as "she")
Stark Raving Dad; Treehouse of Horror VII
38. Stinky and Wrinkles (two fish) were killed when Bart smashed their fishtank with a yo-yo; Superdude (a gerbil)
died when his water bottle fell on him
Bart the Lover; Who Shot Mr. Burns?, Part One
39. Milhouse
'Round Springfield
40. They have an aquarium with fish in it; also, Bart has (or at least had, before he left it in Australia)
a frog
Rosebud; The Crepes of Wrath; Bart vs. Australia
41. Darryl Strawberry
Homer at the Bat
42. Doris Grau
Marge vs. the Monorail
43. Butterscotch (Bart), imitation butterscotch (Bart), seafood (Marge), strained pears (Maggie - and note
that's "pears", not "peas")
Blood Feud; New Kid on the Block; A Streetcar Named Marge
44. The Amos & Andy Show (which really was sponsored by a beer company)
Duffless
45. Homer, Bart, and Lisa; Marge's only lines in Krusty Gets Kancelled were cut (she was in a traffic jam caused by the billboard), while Maggie does not appear, much less "speak", in The Front
46. Dan Castellaneta plays the man who's with the woman next to the disguised monsters when they steal Charles Barkley's talent; Frank Welker is the voice of Michael Jordan's dog Charles
47. Hey Arnold!, with Dan Castellaneta as Arnold's grandfather and Tress MacNeille as Helga's mother, and Rugrats, with Tress MacNeille as Angelica's mother
48. L.A. Law; Dan Castellaneta played someone who worked as a costumed Homer Simpson at an amusement park but was fired for taking off his mask (he was overheating); to show how hot the mask was, the lawyers got the jurors to put on the masks (and note that Dan's face was never shown when he used his Homer voice, presumably as part of the policy to make the characters "as real as possible" by not having the actors do the voices on TV, although at least one has)
49. "Ay Caramba" (any answer with an E or a U is incorrect - "Aye Carumba" has two mistakes in it)
50. The real one has Bart riding a skateboard, whereas the one on the show does not