Recycled Animation

Homer Vs. Lisa and the Eight Commandment / King Size Homer / The Old Man and the Lisa

This establishing shot of the grocery store has a trolley rolling into the road. This may have been in more episodes - in fact I have noticed many episodes with a static opening shot of the same store (i.e. without the trolley).

Bart Vs. Thanksgiving / Radio Bart

This scene with Lou and Eddie was used for both these episodes... in both cases regarding Bart.

Brush With Greatness / Bart the Murderer

The animation for Burns' "Somebody up there likes me" speech in Brush With Greatness was reused in Bart the Murderer.

Lisa's Substitute / Bart the Murderer

This scene was originally used at the end of Lisa's Substitute, when Homer is on "the biggest roll of his life". The animation was reused for Bart the Murderer after Homer has been to the "Legitimate Businessman's Social Club" (where Bart is working).

Stark Raving Dad / Homer's Triple Bypass / Homer and Apu

This short scene with the ambulance was used in these three episodes (and maybe more). The license plate reads "SLIP".

Stark Raving Dad

This montage of people being told Michael Jackson is coming to town is made up of nine scenes from older episodes:

1. The War of the Simpsons
2. Principal Charming
3. Homer's Night Out
4. Bart's Dog Gets an F
5. When Flanders Failed
6. Bart's Dog Gets an F
7. Some Enchanted Evening
8. Old Money
9. Blood Feud

Moaning Lisa / One Fish, Two Fish, Blowfish, Blue Fish

This short scene of Homer eating Pork Rinds Lite was reused after Homer vows to "live life to its fullest". It is looped over and over during the credits, with different background noise from the television.

Bart's Dog Gets An F / Lisa's Pony

In Lisa's Pony, Lisa calls Homer at work. The shot of her on the phone is reused from Bart's Dog Gets An F. An odd choice, since she had the mumps in that episode. Homer putting down the phone is also recycled from the former episode.

Lisa's Pony

The shot of Homer being woken up by the phone is used twice in this episode: firstly in the fade from "The Dawn of Man", and secondly when Lisa calls Homer at work.

Saturdays of Thunder / Radio Bart

An opening shot into a Homer/Marge bed scene. Both times Homer was talking about Bart.

Radio Bart / Dog of Death

This shot of Homer was used in Radio Bart for the line "Bart's birthday is coming up" and was reused for his "And I'll be right here watching TV!" line from Dog of Death.

Homer at the Bat / Lisa's First Word

This animation was used when Homer was making his bat, and again when he made Bart's clown bed.

Homer Defined / Treehouse of Horror II

This scene was used at the beginning of Homer Defined, where Homer reads USA Today and Lisa gives her opinion. It was reused in the final scene of Treehouse of Horror II, where Homer argues with his second head (Mr. Burns).

Note that in this shot, Lisa is next to Maggie and on the opposite side of the table to Homer, however in Treehouse of Horror II, in the next shot she is sat next to Homer (without the newspaper) and Maggie is on the opposite side of the table to her.

Separate Vocations

This sequence of eight shots below, part of the random locker search, was repeated twice:

Homer's Barbershop Quartet / 'Round Springfield

Abe listens to the radio: "Baby on Board" in the former and Bleeding Gums Murphy's album in the latter.

Marge on the Lam

This episode has some recycled footage, but I'm not sure exactly which episode its from. The image shows a cut from the den at the front of the house to the TV room, which is at the back of the house, when Bart says the line "we don't need a babysitter".

Saturdays of Thunder / Homer Alone

This shot of Homer answering the phone was used in both episodes, with ironic "on hold" music for each: "Cats in the Cradle" when he rang the Fatherhood Institute, and "Baby Come Back" when he rang the police station to report Maggie missing.

Homer's Odyssey / Bart the Daredevil

In Homer's Odyssey, Otto drives the kids to the nuclear plant. In Bart the Daredevil, he is driving them to Springfield Gorge. This short animation of the bus passing Springfield Prison was reused.

Homer Alone / Brother, Can You Spare Two Dimes?

Another Homer/Marge bed scene. The same animation was used for both of these episodes.

Saturdays of Thunder / Homer Loves Flanders / Sunday, Cruddy Sunday / Homer the Moe

These two American Football shots (the first is from Saturdays of Thunder, the second from Homer Loves Flanders) were reused in Sunday, Cruddy Sunday to advertise the Superbowl. The second one was reused again in Homer the Moe. I think they have been used in more episodes but I am not sure.

Dancin' Homer / Homer at the Bat

The pan across the stadium from Dancin' Homer was reused at the end of Homer at the Bat, as the fade into the "Talkin' Softball" song over the credits.

Bart The Daredevil / Marge Vs. The Monorail

This animation for the Truckasaurus commercial was reused in the monorail episode as an advert for "Truckasaurus: The Movie".

The Front

This scene of Roger Meyers Jr. throwing his name block at a writer was used twice in the episode, as was the animation of him laughing.

Krusty Gets Busted / Another Simpsons Clip Show

After an Itchy & Scratchy episode, the kids laugh and Marge walks in and comments on it. In the clip show, the Itchy & Scratchy cartoon they watched was reused from an earlier episode, but not Krusty Gets Busted. Also note the crude cut back into new animation.

One Fish, Two Fish, Blowfish, Blue Fish / Another Simpsons Clip Show

This scene of Bart with a fork of food was first used in the former, and then twice in the latter: for the lines "What happened to Mindy?" and later for "We learned [love] screws everybody up".