Audio problem: During the opening overture, right when the orchestra starts "Maria", you can hear someone sneeze in the background. It's easier to hear on the soundtrack but you still can hear it in the movie.
Continuity: In the fighting scene between the "Jets" and the "Sharks" towards the beginning, when Bernardo cuts Baby-Jon on the cheek, the cut clearly switches from one cheek to the other between the time of him being cut, to when speaking to the police officers.
Continuity: Near the end of the movie, when Maria (Natalie Wood) is kneeling over Tony's (Richard Beymer) dead body, watch the cross around her neck. first it's sort of tucked into the top of her dress, then it is on the outside. it goes back and forth several times.
Continuity: In the prologue, when the Jets are talking about Tony, Ice goes, "Man, remember them fists the day we clobbered the Emeralds." you can see A-Rab with his arms crossed. In the next shot they're uncrossed and he crosses them.
Continuity: When Maria is hitting Tony while saying "Killer," her hair is across her left cheek. In the next shot, it is completely away from her face.
Other: In the prologue, after Riff stands up and signals to the other Jets to follow him, they all stand up, then in the next shot you can see Baby John stand up again.
Continuity: In the playground, when the Jets stand up, the guy with the violet t-shirt stands up twice.
Continuity: The blonde guys snapping fingers, one with a violet t-shirt and the other with a red shirt, stand close to each other, but half a second later stand further apart.
Deliberate "mistake": The knives at the rumble bend EVERY time they move.
Continuity: In the scene right before "cool" when the two girls are crying, when they enter the garage their clothes are different.
Continuity: During the rumble, Riff slashes at Nardo's shirt with his knife and he spins away, but you can't see any tear in his shirt. Then in the next shot, when Riff is running toward him again there's a noticeable cut in his shirt (on the back).
Other: During "Cool," there's a shot where they're doing a sort of knee turn, and you can see Tucker Smith in the background spinning too many times (you can see him start to stick out his arms to stop himself).
Other: When Nardo is piercing John's ear, it's obviously just him and the Sharks, but then in the shot from above, you can see all the Jets running to the rescue. Also, Ice is already there, throwing a Shark off of John.
Revealing: In the final scene, if you look in the background that is completely opposite of the gate where the characters exit, there are two cars obviously made of cardboard. Many times they can be seen by looking over Maria's shoulder.
Continuity: At the gym during the dance, Baby John tells Riff, "Pick up" when Nardo and the Sharks come into the gym, and all the Jets stop dancing - except for Ice and Velma. Then in the next shot, Ice is suddenly in the big Jet mob, and Velma is off to the side with Graziella.
Continuity: Toward the end of the movie when Doc slaps Tony, Tony grabs his face. Then they show a behind shot of Tony and you can see his hand moving slowly away from his face. But when they show a front shot of Tony his hand is back on his face.
Continuity: When Bernardo catches the basketball, the Jets are divided on two separate groups. Half a second later the next angle shows a closed single group.