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.
When the leader of the Scorpions escorts Rizzo into the dance hall, he removes his sunglasses. In the next shot, he removes them again.
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.
During the Hand Jive, Sonny runs up behind Patty Simcox right before her skirt is lifted. For reasons unknown, Sonny was replaced by Kenickie for this part.
In "Greased Lightning" they put white letter tires on Greased Lightning which weren't around until at least the late-1960s.
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.
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!"
Marty was the one who said "hey look, it's Jan!"
Marty's kneepad exposed when sliding at the end of the big dance.
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 drag race, 1970s trucks and cars are driving on the overpass in the background.
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.
During the 'Greased Lightning' dance set, when Danny (John Travolta) is on Greased Lightning: a US Flag is mounted on the wall, which bears the modern 50-star design (evident by the alternating star pattern in the union/canton of the flag). Since the film is set in 1958 (before Alaska and Hawaii became states), it should be the 6x8 48-star set up.
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.
While singing "You're the One That I Want," Danny and Sandy spin twice in the amusement park. The second twirl is not perfectly in sync with the music.
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. (In the 2006 Rydell High edition, the boom mic has been digitally erased.)
When Danny is about to play basketball and the coach is talking to him, the boom mic's shadow is visible behind the coach.
After Eugene pies Coach Calhoun in the face, Calhoun says to him, "I want you," [on a team]. Eugene is a graduating senior.
At the dance, Danny wears a 1970s leisure suit with a pink shirt. In 1959, pink shirts on men were considered a mark of homosexuality and would have been avoided by anyone trying to maintain a macho image.
When Kenicke and Danny are hugging after his "number two" speech Kenicke's cigarette flies off from behind his ear.
At the drive in John is on the car instead of Danny.
Marty Maraschino pronounces her name "mare-eh-SHEE-no" but it is actually pronounced "mahr-ah-SKEE-no."