Blackboard Joke: Spitwads are not free speech.
Couch Gag: The Simpsons sits on the couch, Santa's Little Helper can be heard whining; Homer reaches under his ass and pulls the dog out from under him.

Lisa: I don't think real checks have exclamation points.

Homer: (opens a sweepstakes junk mail with a `You may have already won check) One million dollars! I'm rich! (rushes off to the bank)
Teller: Mr. Simpson, I can assure you, this check of yours is non-negotiable.
Homer: Oh yeah? Well, what makes you so damn sure?
Teller: See where it says, "VOID VOID VOID'' and "This is not a check," "Cash value one twentieth of a cent'', ``Mr. Banker, do not honor''...
Homer: Shut up.

Homer: (reading 'Reading Digest') Hey, a cartoon! (cartoon shows a woman tries to explain a pile of metal that used to be a car)
Homer: (reads the cartoon caption) "Well, dear, you always wanted a compact...'' (laughs) Ain't it the truth!
Marge: No, it's not the truth, Homer. It's well-documented that women are safer drivers than men.
Homer: Oh, Marge, cartoons don't have any deep meaning. They're just stupid drawings that give you a cheap laugh. (gets up, revealing butt crack)

Bart: (reading a sign) On this spot, Richard Nixon bowled back-to-back 300 games.
Homer: Yeah, right.

(Marge admiring the Washington Monument and then chuckles)
Homer: Hey, what's so funny?
(Marge whispers)
Homer: Oh, Marge, grow up.

(Lisa walks up to the Jefferson Memorial statue)
Lisa: Mr. Jefferson, my name is Lisa Simpson, and I have a problem.
Jefferson: I know your problem. The Lincoln Memorial was too crowded.
Lisa: Sorry, sir. It's just...
Jefferson: No one ever comes to see me. I don't blame them. I never did anything important. Just the Declaration of Independence, the Louisiana Purchase, the dumbwaiter...
Lisa: Uh, maybe I should be going. I've caught you at a bad time...(begins walking away)
Jefferson: Wait! Please don't go. I get so lonely...

Faith: Will the winning essay be...Bubble On, O Melting Pot, Lift High Your Lamp, Green Lady, USA A-OK, or Cesspool on the Potomac?
Bart: (wishing aloud) Cesspool! Cesspool! Cesspool! Cesspool!

The first time that we see all 3 children staring at the TV, the inside of the Simpson house seems slightly different.

The Simpsons take a flight to D.C. for Lisa's speech. But it's revealed in a later episode that Marge is afraid of flying. This was before it was discovered that she had a fear of flying.

When Lisa is reading her speech for the essay contest, what she says doesn't match the movement of her mouth.

Mr. Smith Goes To Washington

The title Mr. Lisa Goes to Washington is a reference to the movie Mr. Smith Goes To Washington from 1939. Read more about the movie in the wikipedia article.

Reader's Digest

Reading Digest was a play on words for the Readers Digest magazine, first issued on February 5, 1922. The magazine contains condensed stories and articles from other publications combined in a small, pocket sized booklet.

Alice In Wonderland

The subject for a painting on a congressman's wall was from the story Alice In Wonderland.