Continuity mistake: When Dally falls off of his chair in the drive-in movie theater, you can hear Ponyboy's laughter above them all. When the shot changes to Cherry, you can see Ponyboy with a serious face on in the background but you can still hear him laughing.
Plot hole: The pictures used in the newspaper article regarding the fire are obviously taken after Ponyboy and Johnny ran away since Pony's hair is blond and Johnny's is short (their hair was cut and dyed after they ran, ruling out the photos being old school photos), yet Johnny's face is free of burns. This would mean the pictures were taken while they were hiding in the church, which would be impossible.
Continuity mistake: In the shot where Johnny has just killed Bob, the Soc, Bob is lying with his head to the side. But when Johnny cleans his blade from Bob's blood, Bob is facing upward in the background.
Visible crew/equipment: When Pony Boy, Dally and Johnny are pulling up to the burning church, just before the first one jumps out of the car if you look through the windshield you can see the water truck that's going to put out the fire after they shoot the scene.
Continuity mistake: When Dallas is helping the kids out of the church during the fire, the boards covering the window change from shot to shot; first they are ripped out so you can see his waist and then they are as high as his chest.
Continuity mistake: When everyone is at the movies and Cherry throws her soda in Dally's face, he's dripping wet; you can see him blinking soda out of his eyes. A few lines of dialogue later, his face is completely dry, even though he didn't wipe it off with anything. It couldn't have dried so fast.
Continuity mistake: In the drive-in scene where Ponyboy and Cherry get up to get popcorn and soda, Ponyboy leaves with the popcorn Dallas gave him. They both purchase more popcorn and soda in the snack bar yet when they return to their seats, Ponyboy only has the popcorn he left with and Cherry has nothing.
Continuity mistake: In the first few scenes Johnny's scar keeps changing size.
Continuity mistake: When Dally robs the magazine store, as he takes the money and runs away you see the shop keeper reach downwards for his gun, but in the next shot his hand is up in the air holding it. It's far too quick for a normal person to carry out.
Continuity mistake: There is blood on the edge of the fountain after Johnny stabs Bob; the blood vanishes in the rest of the shots.
Continuity mistake: When Ponyboy and Randy are talking, the camera keeps switching back to Two-bit making fun of the other Socs. When it does this you can see Ponyboy and Randy in the background. If you look carefully at Randy his arms are resting down the side of the car, but when the camera goes back to him as a close up his arms are resting on the roof of the car. This happens several times.
Continuity mistake: When Ponyboy is getting jumped, the Socs try to stick a handkerchief in Ponyboy's mouth, and while they run away the handkerchief disappears.
Factual error: The story is set in 1965, yet it shows many modern (as of filming in 1983) pieces of medical equipment, such as disposable plastic nasal cannula, modern plastic IV tubing and cut offs, etc. Also most hospitals in the 1960s still had open wards with many patients cordoned off by curtains, instead of private rooms as depicted in the movie.
Deliberate mistake: During the rumble scene there is a "Soc" whose clothes are completely dry and clean right before the Socs surrender. He's wearing a light blue shirt.
Continuity mistake: In the church when Ponyboy is reading Sodapop's letter, Dally is in the background with his left hand on his leg. When the shot switches to Dally, his hand is not on his leg, and he is lighting a cigarette. When the shot switches back to Ponyboy, Dally's hand is back on his leg.
Continuity mistake: In the scene where Two-Bit and Ponyboy are visiting Dally in the hospital, when Dally asks Two-Bit for his switchblade, he extends his right arm back for it, and his left arm is under the sheets. In the next shot, his left arm is extended backwards, even though there was no time to switch arms.
Revealing mistake: When Ponyboy and Dally visit Johnny at the hospital to tell him the Greasers won the rumble, Johnny dies in front of them. If you look closely in one shot, you can see slight breathing (rising and falling) under the cot blankets.
Revealing mistake: When Two-bit Mathews returns from the hospital gift shop with a copy of "Gone With The Wind", he hands the book to the nurse asking her to make sure that Johnny gets it. The book he hands her is an obviously used paperback with the upper front top right corner and pages all bent back. Shouldn't a gift shop sell NEW items? The book is only shown from the non-title side so they could have used any paperback for the prop as long as it looked like it wasn't several decades old.