Homer's Barbershop Quartet - S5-E1
Character mistake: When Marge is making a model of Homer for Bart and Lisa, she makes him bald with his hair round the back of his head as we all know it, but at this point in the story Homer was not yet bald. (00:18:15)
Homer's Barbershop Quartet - S5-E1
Continuity mistake: When you see a shot of the church from outside in the scene where the bee sharps sing there, look closely at the sign. It says 'Also: The Bee Sharps', only they don't name themselves that until later on in that episode.
Homer's Barbershop Quartet - S5-E1
Continuity mistake: In the flashback where Marge is making a model of Homer, the models head falls off and Santa's Little Helper picks it up, but the Simpsons did not own the dog back then.
Homer's Barbershop Quartet - S5-E1
Audio problem: When the Bee Sharps are singing 'Goodbye my Coney Island Baby' next to the Statue of liberty, you can hear Chief Wiggum's voice singing with the other members of the group, but he got chucked out of the group earlier on in the episode.
Homer's Barbershop Quartet - S5-E1
Continuity mistake: At the sale, when Bart and Lisa first find 'The Bee Sharps' album, the order of the records in the stack change in subsequent shots.
Homer's Barbershop Quartet - S5-E1
Audio problem: When Homer is playing on the piano, he says the word "fault". When he says this you can hear a key being pressed but Homer doesn't touch any keys.
Homer's Barbershop Quartet - S5-E1
Continuity mistake: At the end of the episode, while the B-sharps are singing on top of Moe's Cavern, the guy climbing the building asks the people to look at him. As he moves his hands, his gloves change color from red to white and back to red.
Homer's Barbershop Quartet - S5-E1
Audio problem: When grandpa is listening to the radio, he says something like 'oh.', but his lips are not moving.
Homer's Barbershop Quartet - S5-E1
Other mistake: When the Be Sharps are singing at the Statue of Liberty, in some shots the stars in the sky are black.
Homer's Barbershop Quartet - S5-E1
Audio problem: After Jasper has sung on the stage to Homer, Apu and Skinner, they simultaneously say "Next". But if you listen carefully you can't hear Homer's voice.
Homer's Barbershop Quartet - S5-E1
Other mistake: When Bart and Lisa are looking at records, there is a picture of Homer. He had hair at the time the record was made, and the hat he's wearing isn't big enough to cover it, but there's none visible as there should be.
Homer's Barbershop Quartet - S5-E1
Continuity mistake: When Homer is talking to George Harrison, he sees that he has a brownie. Then he rushes over to a pile of brownies and starts scoffing them down. The pile of brownies doesn't get smaller.
Homer's Barbershop Quartet - S5-E1
Audio problem: In the scene where the Be Sharps first sing "Coney Island Babe" (I don't know what the song's really called) at Moe's, Skinner sings the rhythm. But when they sing the last few lines, you can still hear Skinner's part, but his mouth is moving like the rest of the group.
Homer's Barbershop Quartet - S5-E1
Continuity mistake: In the deleted scene where the Be Sharps unveil 'Donut Records', Barney's hair flashes red a couple of times in the close-up of the band.
Homer's Barbershop Quartet - S5-E1
Continuity mistake: Homer and Marge's bedroom has photos of Bart and Lisa when they were 10 and 8 years old. However, the story takes place when Bart and Lisa were only 3 and 1.
Homer's Barbershop Quartet - S5-E1
Continuity mistake: When Bart and Lisa find the record Melvin and the Squirrels, they hand it to the Comic Book Guy to play. While the record is in his hand you can still see it displayed on the rack.
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.