Continuity mistake: When the three T-Birds go to moon at the TV camera at the National Dance Off, Doody says "1, 2, 3, go!" and pulls down his trousers to his ankles. In the next scene, his trousers are suddenly pulled right up to his buttocks.
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.
Continuity mistake: In "We go together" they all dance forwards. When the camera changes angle Frenchy and Doody have switched sides.
Continuity mistake: Sandy walks over to meet the girls after doing a cartwheel. On Sandy's cheerleading uniform, there is a LONG red string right next to the letter on her shirt. Then, suddenly, the string disappears in the very next shot. Then in the scene after that it is back again, and then the string is back on her shirt. (00:22:20)
Continuity mistake: During the slumber party at Frenchie's, when Rizzo brings out the wine, check out the junk on the headboard. Later in the scene when Marty is putting on her robe, the headboard is clear and now has a black fan on the left. Then even later when Jan says "You ain't getting your hands on my ears" the headboard is cluttered again, with the black fan too. (00:27:35)
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.
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.
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: When Patti gets her skirt lifted up at the dance contest, the two boys who were dancing on either side of her in the previous shot have both disappeared.
Continuity mistake: When Danny and Cha-Cha are dancing to 'Born to Hand Jive', watch the position of Principal McGee. During the song, you can see her in the crowd. A few shots later, she is now standing near the stage on her own, and when we return to Danny and Cha-Cha dancing, you can see the Principal back in the crowd again.
Continuity mistake: On the first day of school during lunch, at one point Frenchie has out a small compact and is checking for food in her teeth. But when it cuts to a wider angle, suddenly the compact is gone, and she's looking over her shoulder.