Movie Goof (revealing mistake): All of the actors are far past the typical high school age of 14 to 18 years and do not accurately represent high-school aged children: John Travolta (Danny) was 23 years old at the time of shooting; Stockard Channing (Rizzo) was 33 years old; Olivia Newton-John (Sandy) was 29 years old; Both Barry Pearl (Doody) and Jeff Conaway (Kenickie) were 27 years old; Michael Tucci (Sonny) was 31; Kelly Ward (Putzie), at 21 years old, was the youngest of the bunch, while Didi Conn (Frenchy) was 26 years old at the time of filming.
Movie Goof (continuity error): In the dance-off, just before Cha-Cha replaces Sandy as Danny's dancing partner, there is a wide shot of Danny and Sandy dancing. In the corner you can see Cha-Cha walk out from behind some students. The camera then makes a close-up and she repeats the same movement.
Movie Goof (continuity error): During the last part of the racing sequence, along the river's banked edge, Leo's black convertible loses its front license plate, only to have it re-appear moments later.
Movie Goof (continuity error): Sandy's "R" streamer on her sweater at the pep rally.
Movie Goof (anachronisms): During the drag race, modern trucks and cars are seen driving on the overpass in the back ground.
Movie Goof (continuity error): When Frenchie is about to pierce Sandy's ear, the bottle of wine switches between Jan and Sandy in between shots.
Movie Goof (anachronisms): During the first dance in the gymnasium ("Rock and Roll is Here to Stay") when Danny and Sandy are dancing near the end of the song, there is a scoreboard visible very briefly which reads either "Presented by class of 1971" or "Presented by class of 1974", far later than the time when the story takes place.
Movie Goof (boom mic visible): The boom mic is reflected in the jukebox when Danny tells Sandy he has an image to protect. (In the just-released Rydell High edition (10/06), the boom mic has been digitally erased).
Movie Goof (audio/visual unsynchronized): When Sandy clicks her tongue after her big change.
Movie Goof (continuity error): As Rizzo being escorted into the dance hall by the leader of the Scorpions, he removes his sunglasses. In the next shot, we see him remove them again.
Movie Goof (continuity error): In the lunch scene, when Rizzo and Marty first sit down, there's a half eaten apple in front of Rizzo's lunch tray that keeps disappearing and reappearing between shots.
Movie Goof (continuity error): As the Scorpions drive past the malt shop, Kenicke can be seen pointing at them and lowering his right hand twice.
Movie Goof (audio/visual unsynchronized): In the final sequence while singing "You're the One That I Want," Danny and Sandy spin twice in the amusement park walkthrough (The Shake Shack). On the second twirl, you can tell that it is not perfectly in sync with the music.
Movie Goof (continuity error): During Summer Nights, Rizzo's shades repeatedly jump between her face and her hand between shots.
Movie Goof (revealing mistake): When Sonny snaps Tom's suspenders as he is walking into the gym, a very visible microphone can be seen on the top right corner, and also part of the crew can be seen in the bottom right corner.
Movie Goof (continuity error): While in the shake shack, some of the close-ups do not match the other scenes, in the far shots there are people and trees behind the bars, in the close-ups there are neither, and also the wall colors are different between shots.
Movie Goof (anachronisms): The jukebox in the diner is a 1973 Wurlizter 1050 (which copies the design of the famous 1015), yet movie is set in 1959.
Movie Goof (revealing mistake): During "Greased Lightning" when the motor is dropped in the car and the fan is spinning, a string can be seen for a second making the fan spin.
Movie Goof (continuity error): During the fast dancing, there is bright daylight coming in through the gym windows. Seconds later, they turn down the lights for the "Blue Moon" slow dance. The gym is totally dark. This would be impossible since there was daylight coming in through the windows seconds ago.
Movie Goof (boom mic visible): When Danny is about to play basketball and the coach is talking to him you can see the boom mic's shadow behind the coach.
Movie Goof (anachronisms): The TV truck (shown briefly before the scene in the gym) includes two roof-top air conditioners. These were not produced until the late 70s.
Movie Goof (continuity error): During the final musical number, "We Go Together", at the carnival, the shadows on the ground change from short to long and back to short again.
Movie Goof (continuity error): In the closing number, "We Go Together," Doody and Frenchy switch places between the lines, "When we go out at night/And stars are shining bright." Also, the blonde guy to the left of them goes from a sitting position to a standing position in the same error.
Movie Goof (continuity error): At the start of the 'National Bandstand' dance-off (the "Born to Hand Jive" number), the head of the cowboy decoration in the gym tips forward, spilling wads of paper off the brim of its hat. However, in the establishing shots prior to that there is no paper on the hat brim. In addition, a few seconds later, and as seen in other shots that follow, the head is intact and back in proper position.
Movie Goof (continuity error): During the dance scene, when the teachers are congratulating Patty and Eugene, Eugene starts waving to the students. In the next shot, when the camera is facing the stage, he and all the other students are standing still.
Movie Goof (continuity error): In one scene at the diner, Doody hands over a banana split to Frenchy. As the camera angle changes he is seen handing over the same banana split again.
Movie Goof (audio/visual unsynchronized): At the cotton candy stand, Blanche is seen silently mouthing the question, "How many?" Moments later, from a different camera angle, the same question is asked - this time with audio intact.
Movie Goof (anachronisms): Frenchey makes a comical reference to the old advertising slogan "the heartbreak of psoriasis" years before the phrase was actually introduced in a 1964 Tegrin ad campaign.
Movie Goof (incorrectly regarded as a mistake): On the first day of school, Sandy mentions that there are 86 days until Christmas vacation. She means school days until Christmas, not total days.
Movie Goof (continuity error): In the diner, Vai turns off the lights with her elbow, despite missing the switch by six inches.
Movie Goof (continuity error): During the drag race after the white Ford jumps the hood pops open, the grille falls out of place, and the trunk opens up, but in the next shot the only damage is a crooked bumper.
Movie Goof (revealing mistake): Marty's kneepad exposed when sliding at the end of the big dance.
Movie Goof (continuity error): In the beginning of "You're the One that I want" Danny Zuko falls down in the dirt and when he gets up his black shirt is dirty in the belly area. Also, Olivia Newton-John's character 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.
Movie Goof (continuity error): A dummy is being burned in effigy during the pep rally; however, the amount of flames on the dummy goes from small to large (the dummy is fully ablaze) then back to small (a closeup shows the fire only on the upper torso and one can still read the undamaged sign on the dummy).