Revealing mistake: There's a short ramp by a truck's cargo bed, but when the bikers ride over it, it's become a longer ramp that goes up to the cabin to allow for the stunt. (00:06:14)
Visible crew/equipment: When Ponyboy, 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.
Other mistake: In the end credits, Santa's name in the song title "Santa Claus is Comin' to Town" is misspelled as "Clause."