At, the very end, when Dally robs the convenience store, he pulls out his gun at the store clerk and he points it on the clerk's right cheek (at 01:23:27 in 91 m.). The next shot of the clerk, shows the gun on the left side of the clerk's cheek (at around 1h 23 mins).
During the Rumble, when all the Greasers are lined up, Ponyboy is on Darry's right (at 01:13:35 in 91 m.), but when Darry turns to Ponyboy to tell him to stay close, Ponyboy is on Darry's left (at around 1h 14 mins).
When Dally is in the hospital on his bed, he asks for a pocket knife. In the first shot he is reaching with his left hand while his right hand is under the blanket (at 01:05:33 in 91 m.). In the next shot, he is reaching with his right hand (at around 1h 05 mins).
When the boys arrive at the church fire, Johnny opens his door on the passenger side of the convertible twice (at 48:38 and 48:49 in 91 m.).
During the rumble, the Greasers and Socs are alternately wet/dry between shots, and the mud on Paul's white pants appears, and disappears, etc.
The peroxide that Johnny buys for Ponyboy's hair would NEVER achieve the near-platinum blond results, not even close.
Dallas falling out of the chair at the Drive-in (at 07:18 in 91 m.) was an accident and was not rehearsed. Ponyboy looks at the camera expecting Francis Ford Coppola to say cut, but they kept the shot instead.
After the boys come over for breakfast near the end of the movie, Ponyboy goes out on the porch. When he goes out (at 55:13 in 91 m.) there is a rip in the screen in door. When he comes back in the rip is gone (at around 26 mins). This is because the screen is pulled away from the frame near the door handle which can be seen when the door is open (55:13), but not when the door is closed (55:26).
Just before the Socs attack Ponyboy, he taunts them (in retaliation to their comments) by saying, "You know what a Soc is? White trash with Mustangs and Madras." The subtitle reads, "You know what a Soc is? White trash with Mustangs to match." ("Madras" is a lightweight fabric used for summer wear, so he is referring to their "classy" outfits in comparison to the Greasers' T-shirts and jeans).
At the Dairy Queen, Dally says, "She pulls up in a little old Stingray." The subtitle reads, "She pulls up and we're all staring at her."
Just before the rumble, Darry says to Ponyboy and Johnny, "You two will get the boys' home, you know what I'm saying?" The subtitle reads, "You two will get the boys' home, understand?"
When Dally uses phone (at 01:24:07 in 91 m.), a tilted In-and-Out burger cup is visible. There were fewer than 20 open at the time, and only in Southern California.
When Ponyboy and Johnny go to the bar to see Dally, there is a song playing on the jukebox called 'Jack Daniels if You Please' by David Allan Coe. This song was written and released in 1978 although the movie takes place in the 1965.
The story is set in 1965, yet it shows many modern (as of filming in 1983) pieces of medical equipment, such as disposal plastic nasal cannula, modern plastic IV tubing and cut offs, etc. Also most hospitals in the 1960s had open wards with many patients cordoned off by curtains, instead of private rooms as depicted in the movie.
The movie is set in 1965. However, when Dallas is reading the magazine, just before he robs the convenience store, comic books from DC Comics and Charlton Comics are shown with logos that were introduced in 1977 and 1973 respectively. Three comics can be clearly seen: Detective Comics #521, Fightin' Marines #166 and Captain Carrot and His Amazing Zoo Crew #10. All three comics were originally published in December 1982.
It is stated the film takes place in 1965, yet at least one car has 1966 on the license plate.
When Dally, Johnny and Ponyboy are watching the movie at the drive in, Ponyboy starts laughing, but in the next shot we see Ponyboy in the background not laughing while the audio track of his laughing is still continuing (at 07:23 to 07:25 in 91 m.).
As Ponyboy, Johnny and Dally are walking to the movies, when you see them walking in front of the store, the boom mic (and its operator) are reflected on the windows (04:47 to 04:53 in 91 m.).
When Ponyboy is reading the newspaper article about the church fire, the paper spells his name Pony Boy Curtis, rather than Ponyboy (at 53:57 in 91 m.).