Factual error: At the graduation carnival at the end of the movie, Danny enters wearing a letterman's sweater and explains to his buddies that he earned it by lettering in track. However, on his left sleeve are two stripes, indicating that he lettered in two separate years. Since you are only awarded a stripe for each year you letter, and since Danny was a senior when he lettered in track, his Rydell letterman's sweater should have had only one red stripe on his left arm.
Continuity mistake: At Frenchie's sleepover when they are talking about piercing Sandy's ears, it shows Sandy holding the wine bottle and passing it to Jan. Then it cuts back to Sandy and she is still holding the wine, then it cuts back to Jan and she has the wine again.
Continuity mistake: When "Crater Face" comes to the dance with Marty and Rizzo, he takes his sunglasses off twice.
Continuity mistake: In the scene where the whole gang is eating at the soda shop, everybody starts leaving. Doody is in the back, in the middle, on the railing. He's getting ready to leave, takes a bite of his ice cream and sets it down. In the next shot, he sets it down again.
Revealing mistake: At the dance, there's a scene where everyone started dancing after Cha-Cha and Danny won the trophy. Well Marty comes in from the side of the screen and lands on the floor in some kind of split, and you can see she is wearing a knee pad on her right knee.
Factual error: When the Pink Ladies are walking Sandy into the outdoor cafeteria, just after she tells them the name of the boy she met last summer, all the cars in the background are from the 70's, not from the late 50's or early 60's. This actually happens twice in the same scene.
Continuity mistake: In "We go together" they all dance forwards. When the camera changes angle Frenchy and Doody have switched sides.
Continuity mistake: When Marty is talking to Vince Fontaine before the dance contest, towards the end of their conversation she starts to lift up her purse with her right hand. But suddenly it cuts to another angle, and her arm is down.
Continuity mistake: In the middle of the dance contest, Patty Simcox does a funny front walkover, and comes dancing towards the camera. Over her shoulder, you can see Sonny running up behind her. But suddenly it cuts to another angle, and Kenickie is running up behind her to lift up her dress, and Sonny is nowhere to be seen.
Revealing mistake: When Sandy checks into school for the first time, she goes down to the office and the assistant principal gives her some forms to fill out. If you look closely, you'll be able to see that the top form is just a blank piece of paper.
Other mistake: On the first day of school, when Patty is starting to sit down next to Sandy, her reaction to sitting on the apple is way too early.
Factual error: In the scene where Danny is talking to Sandy at the Frosty Palace, the jukebox behind them is a 1973 model, but the film takes place in 1959.
Continuity mistake: After Danny has danced around the car with the saran wrap he is shown spinning around numerous times, and then stops with his back to the camera. However, in the very next shot, his arms are suddenly up in a pose far too quickly for him to have done in the time alloted.
Character mistake: When Frenchie is the only person remaining in the soda shop a guardian comes on and starts singing a song. While he is singing the song (toward the end of his singing) all the girls scatteringly head back toward the stairs. While they are walking up, one of the girls trips over her high heels. It is clearly shown, she's toward the front going around the back of the seat Frenchie is sitting in, around the round thing.
Continuity mistake: When Danny is first shown at school, he is speaking face-to-face with a girl in a blue sweater. The immediate next shot, Danny is talking to a totally different girl in a purple sweater, and he has his back turned from the camera.
Other mistake: This mistake occurs during the dance sequence 'You're the One that I Want.' John Travolta and Olivia Newton-John have just emerged from a 'Shake Shack' and are now ascending a ramp. For the lyrics ,Hoo hoo hoo... honey,' the camera zooms in close to their faces. You can see that the dance move is for the two actors to bob their heads close to each other's so that they nearly touch. They do it right the first time, but the second time they visibly mess up. John Travolta seems to try to fix his mistake, but Olivia Newton-John appears to crack up and leave the frame.
Continuity mistake: During the car-racing scene, Danny's car has a big scratch in it. For the next few shots, it's missing and at the end of the scene, it reappears.
Continuity mistake: At the dance, when Frenchy insults Cha-Cha by saying, "With the worst reputation", Cha-Cha is shown (in the close-up) first looking at Kenickie, then turning her head around to give Frenchy a dirty look. In the next shot when Danny and Sandy are leaving the group, Cha-Cha is suddenly back at looking at Kenickie, then proceeds to give Frenchy the same dirty look again.
Continuity mistake: The TV set that is in the scene when Jan sings, "Brusha Brusha Brusha" is not the same TV that is shown when Rizzo is getting ready to go out the window during the slumber party.
Visible crew/equipment: In the scene where they are singing Grease Lighting - the part when the fuzzy dice float to Kenickie - after he takes them "out of the air" and swings them around, then lets them fly - if you look close to his head you can see the white string they were attached to when they were "floating".
Answer: It is implied that Danny and Rizzo had a previous romantic relationship of some kind. When Jan says, "Did you guys get a look at Zuk this Morning? Looking pretty good this year, huh, Rizz?" Rizzo replies, "that's ancient history." Later, when Danny says, "you're looking good, Rizz, " her answer, "eat your heart out," also suggests some possible residual feelings on her part. I think that's why Rizzo enjoys tormenting Sandy and Danny by reintroducing them at Rydell at a moment that she knows Danny is going to save face around his friends.
Michael Albert