Revealing mistakes: You can see Baby's body stocking during the second sex scene.
Continuity: Johnny gets his pants dirty by sliding across the floor, yet they are clean in the next shot.
Continuity: Johnny puts his records back twice after talking to Neil.
Revealing mistakes: After the second "sex" scene when Baby asks Johnny if he's "had many women," she rolls over when he comes back to kiss her after putting his shirt on and you can clearly see her underwear near the top of the sheet across her back.
Factual errors: Driving to the resort at the beginning of the movie, the road has solid center lines which are yellow. In the early '60s centerlines were white, not yellow.
Revealing mistakes: When Baby and Johnny are driving to the lodge, you see their silhouettes in the car, but not their faces. It's obviously a stunt double wearing a very bad big wig.
Continuity: In the last dance scene, when Johnny jumps off the stage and goes to the back of the auditorium to get the other "dirty dancers" his hair is alternately wet/dry between shots.
Continuity: Size of the hole in Johnny's back window changes between shots.
Revealing mistakes: When Johnny has to bust the back window of his car, the shot inside the car shows that the entire window frame gives way, but from the outside shot, there is only a hole and the window frame is in place.
Continuity: When Johnny jumps off the porch to fight the guy who's been taunting him, his belt buckle is buckled. Then, when he lands on the ground and starts fighting, his belt is buckled undone. Then after a punch is thrown it's buckled again.
Continuity: When Johnny locks his keys in his car during a torrential rain, you can see the sun reflected shining brightly in the rear window of the car. You can also see that the ground beside the post he picks up is dry and sunlit and you can see shadows cast by the sunlight as Johnny picks up the post.
Continuity: When Baby is talking to her father as he sits on the porch, his jacket collar repeatedly swaps between being down and up between shots.
Revealing mistakes: When Baby is painting the "end of the season" show's set, their is no paint on her brush which looks clean and unused.
Revealing mistakes: When Johnny first slides on the ground towards the camera, you can see his kneepads in the light.
Audio/visual unsynchronized: When Johnny is driving off after he got fired, you hear the car start up at the same time you see his hand change the gear shift. He never even touched the ignition.
Continuity: After Billy with the watermelons finds Baby in the staff area, they start up the long hill of stairs to the faint sounds of 'Do You Love Me' beginning to play. When they reach the the top in the next frame, presumably 2-3 minutes later, the song is still at the beginning.
Continuity: During the final dance when Johnny gets ready on stage, he can be seen taking his coat off twice.
Incorrectly regarded as goofs: When Johnny locks his keys in the car he breaks the rear window to open the passenger side door. We then see him go round to the drivers door and open it. Baby can actually be seen reaching across the seat and unlocking the door while Johnny is walks around the car.
Revealing mistakes: When Johnny and Baby are driving back to from the other hotel you can clearly see that the car is still in 'park'.
Continuity: In the first scene when the family arrives at the camp, the woman sitting in the passenger seat is not Kelly Bishop who plays Baby's mother, but the actress who was originally cast as Marge. In the next scene when they're getting out of the car, it's actually Baby's mother.
Incorrectly regarded as goofs: In the last scene when Johnny and Baby start the dance, everyone in the audience is seated in a chair. However at the end of the scene there are no chairs on the floor. However, you see some of the male dancers stop dancing and begin moving all the chairs for everyone to join in dancing.
Errors made by characters (possibly deliberate errors by the filmmakers): When Baby is being sawn in half for the magic show she looks at the audience and they're all upside down. When you lay flat everything is still the same way up.
Anachronisms: The "Ludwig" logo on Tito's drummer's drum set wasn't introduced until the early 1970's. Also the drum set has the Ludwig blue-olive badges, not introduced until late 1969 (the movie is set in 1963).
Continuity: Lisa decides to lose her virginity to Robbie. She walks to his cabin that night and when she knocks on the door, there is a white towel on the door knob, a warning that Robbie is "busy". Lisa opens the door and when she closes it, the white towel is gone.
Crew or equipment visible: In the scene where Johnny is teaching Baby how to dance on a log of wood over a river, the safety mats for the actors are visible on the river bed for a quick second.
Continuity: Before the final show/dance, Baby is sitting on her bed getting ready. She is wearing a no-seam bra (not available at the time) and rolling up stockings before putting them on when her sister comes in. When Baby is at the party/final dance, she is wearing a backless dress (no bra) and when dancing, she is wearing pantyhose instead of the stockings (and necessary garter-belt) that she was preparing earlier.
Continuity: Before the final dance sequence, as Johnny leaves the stage he starts taking off his jacket. The camera then cuts to off-stage and his jacket is on and he starts taking it off again.
Revealing mistakes: At the beginning of the "Time of My Life" dance, Billy is seen putting the record on the record player as Johnny takes his jacket off. After the dance when the audience has gotten up and started dancing, Max asks Tito, "You have sheet music on this stuff?" and you see Tito's band playing the song as he is conducting.
Audio/visual unsynchronized: "Sylvia and Mickey" was a warm up and not initially meant to be in the movie, Patrick Swayze himself said so. You can get this confirmed if you pay close attention to Jennifer Grey's lips just before she says: "Don't look down, look right here." Her lips are mouthing "Patrick". They must have muted it after they decided to keep the scene in the movie.
Anachronisms: Jennifer Grey (and several other actresses in the film, actually) sports an obviously '80s "big hair" perm, something that wasn't in-vogue in 1963. Many women during that era went for straight-hair updos or the "Jackie O" bob look.