During the race scene there's a shot of Buzz's left hand cuff caught on a door handle that faces forward. The very next shot shows his left hand on the wheel and his right hand trying to free himself from a completely different door handle that faces backwards. The first door has a stripped upholstery and the next is just plain gray.
When Plato and Jim are at the Planetarium, Plato points to the mansion, located far away in the distance. However when they go the mansion, the mansion and Planetarium seem to be right next to each other, as they can easily run from the mansion to the Planetarium.
Jimmy puts his left hand through the window, but it's a right hand that turns the radio knob.
After Buzz has fallen off the cliff and Jim returns home, the left shoulder of his jacket is dirty. When he lays on the couch it is clean again. As he is arguing with his parents on the steps, when he faces his father, the jacket has the dirt on it, when he turns to face his mother, the jacket is clean again.
When police backup arrives at the Griffith Observatory, the officer approaches the vehicle on the driver's side to talk to the Juvenile Division officer in the back seat. There are two cutaway shots and now the conversation continues on the passenger's side of the car. The officers within the car change sides of the vehicle, too.
Just because Buzz' cuff was caught on the door handle, it wouldn't have prevented him from opening the door.
The planetarium stars bear no resemblance to the actual night sky, and the constellations superimposed on them don't match the actual constellations.
When Jim goes to turn the car radio off, he turns the volume control, but that radio is turned off by pushing the leftmost pushbutton, which is clearly marked "OFF".
When Jim rolls out of the car during the race, the footage is sped up to make it look like it happened faster than it actually did.
When Plato opens his locker on the first day of school he is just putting his key into the lock and the locker door partially opens. He quickly pushes it back to the closed position then proceeds with the key.
After the "chickie run", Jim is shown laying on his living room couch watching his mother coming down the stairs. His head is tilted back, and the camera switches to show the scene from Jim's perspective, with his mother initially seen upside down, then slowly turning to right side up as Jim turns his head. But in the last moment of this shot, Jim's head is shown -- an impossibility since the shot is supposed to show what Jim is seeing.
In the first scene inside the planetarium, the stars on the dome are shown to be moving, quite fast, yet the Zeiss projector (from which the stars are coming) isn't moving at all, and it should be.
The duration of the "chickie run" was obviously extended to heighten its tension and dramatic impact. The cars are seen going far too fast, and for far too long a period of time, to cover the distance to the cliff. At the speed they were traveling over the distance involved, they should have gone over the cliff within a few seconds.
Although the film was made and released in 1955, the alimony check that Plato receives from his dad is dated 1956.
At the end, Jim and his family, the cops and ambulance all leave the observatory, but Plato's family maid, obviously upset at what happened to Plato, is left standing there alone.
When Plato shoots at Jim, Jim's words don't match up with his mouth. And when Jim tackles him a moment later Plato's words don't match up either.
When Plato arrives at the mansion just after Judy and Jim do, after talking briefly, they let him into the house. When he walks into the house and comes up the stairs, a cord is clearly visible dragging on the ground behind him -- probably a cord for the microphone.
When Judy first sits down in Detective Fremick's office, an extra studio light is seen opening up on her, followed by the shadow of a boom mic moving into place.
Near the end, Plato's family maid appears at the observatory, but it is not revealed how she knew where Plato was, nor how she got there.
How did Jim fix his slashed tire at the planetarium after the knife fight? He had thrown his tire iron away over the rail of the outdoor viewing platform so presumably he had no way to put on the spare tire.
When Jim asks Plato what a chickie-run is, he calls Plato by his nickname. But they never introduced themselves in the earlier scenes.
At the end of the movie, Jim and Judy get into their own car, not the police car. The officers don't ask them anything about the death at the cliffs, or what they were doing in this abandoned building.
During the first visit to the planetarium, the deserted mansion is shown as being quite far away. For the final scenes, the main characters would have found it difficult on foot to get from the mansion to the planetarium in the short amount of time portrayed in the film.
When Jim is being interrogated in the office near the beginning of the movie, a boom is clearly visible reflected in the glass above all the actors' head.
When Jim takes the ammunition clip out of Plato's pistol, he fails to remove the round that would have already been housed in the chamber.