Goofs

Vi misses the light switch, but the light still goes out.

When the leader of the Scorpions escorts Rizzo into the dance hall, he removes his sunglasses. In the next shot, he removes them again.

In the beginning of "You're the One That I Want", Danny Zuko falls down in the dirt. When he gets up, his black shirt is dirty in the belly area. Also, Sandy puts her dusty shoe on his shirt as well. Several scenes later, his shirt is clean again and remains clean for the rest of the song.

During "We Go Together", Doody and Frenchie switch places between the lines, "When we go out at night/And stars are shining bright." The blonde guy to the left of them goes from sitting to standing.

In the lunch scene, when Rizzo and Marty first sit down, a half-eaten apple in front of Rizzo's lunch tray keeps disappearing and reappearing between shots.

On the first day of school, Sandy mentions that there are 86 days until Christmas vacation. She is referring to school days, not calendar days.

Danny calls his friends "dorks", a term that first appeared in the 1960s and wasn't in common use until the 1970s.

This could have been an insult developed by Danny and his friends independent of it becoming a popular term in the 1960s.

In the first shot of the slumber party scene, a young female voice says "Hey look, it's Jan!" The voice markedly does not belong to any of the actresses present in the scene.

Marty was the one who said "Hey look, it's Jan!"

"Rama Lama Ding Dong", a song referenced in the lyric of "We Go Together" did not surface until the summer of 1961, when it became a million seller for the Edsels.

These are nonsense words that the students themselves could have come up with in singing the song.

When Danny is trying out for basketball, his shirt reads, "Rydell High School", but the other players' shirts just have "Rydell".

Danny is wearing his generic gym shorts and t-shirt, the other players are wearing basketball tank-top shirts. Danny isn't going to put on the school's basketball uniform if he's only trying out for the team. The fact that one just says "Rydell" and the other says "Rydell High School" is irrelevant as they are different types of shirt.

Marty's kneepad exposed when sliding at the end of the big dance.

Stockard Channing briefly stops singing during the end of "Beauty School Drop-out".

During "Greased Lightning", when the motor is dropped into the car and the fan is spinning, a visible string makes the fan spin.

During the last carnival scene, when Danny and Sandy drive through the dance line in "Greased Lightning", the car's windshield glass is completely gone.

When Danny and Sandy jump back into frame during the end of "We Go Together", Sandy is barefoot.

When Danny and Sandy are dancing near the end of "Rock and Roll is Here to Stay", a briefly visible scoreboard says either "Presented by class of 1971" or "Presented by class of 1974".

During the "Greased Lightning" sequence, when Danny is on Greased Lightning, a US Flag is mounted on the wall which bears the modern 50-star design instead of the 48-star version from 1958.

The band playing at the dance-off are using Fender "Silverface" type amps, a cosmetic style that wasn't introduced until 1968. The amps look like 1970s models.

Frenchie makes a comical reference to "The heartbreak of psoriasis". Tegrin introduced that phrase in a 1964 ad campaign.

After Cha-Cha brings down her scarf to start the car race on Thunder Road, an Amtrak train is visible above the concrete riverbank at the left of the screen. The F40 locomotive and Amfleet passenger cars began service in the mid 1970s.

At the cotton candy stand, Blanche silently mouths the question, "How many?" Moments later, from a different camera angle, she asks the same question, with audio intact.

When Danny pulls the catcher's mask back during baseball practice, the smack of the mask on the catcher's face is heard after the mask hits his face.

During "You're the One That I Want", when it shows Danny and Sandy's friends at the photo booth, Doody is at first not singing the song correctly, then he is.

When Sandy clicks her tongue after her big change.

When Sonny snaps Tom's suspenders as he is walking into the gym, a microphone is visible in the top right corner, and crew members are visible in the bottom right corner.

As Couch Calhoun and Principal McGee are stepping onto the stage at the dance-off, a Panavision camera and its lens shade are briefly visible in the bottom left of the frame. This camera provided the subsequent shot.

When Danny tells Sandy he has an image to protect, the boom mic is reflected in the jukebox.

When Danny is about to play basketball and the coach is talking to him, the boom mic's shadow is visible behind the coach.

When Kenicke and Danny are hugging after his "number two" speech, Kenicke's cigarette flies off from behind his ear.