When Han and Sean are in the RX-7 and talking, the engine tone shifts at least 7 times, as if the car has 7 or 8 gears, most of which have the same ratio and thus engine tone. Sean's hands remain on the steering wheel throughout the drive, yet the shifts still occur. In addition, they do not have the pitch a manual car would have (revs dropping from engaging the clutch, then shifting into the next gear). The two transmission choices for the car were a 4 speed automatic and a 5 speed manual. This is a recurring mistake in the Fast and Furious movie line.
Various boosted cars (such as the RX-7) do not make the signature sounds of upgraded turbocharged cars throughout the film, such as the turbo spooling and the blow-off valve, until they "hit the nitrous." Nitrous does not change the car's sound.
When Sean and Han escape Han's shop, they drift while trying to evade D.K. and his crew. They would have much better chance if they drove in a clean line, instead of drifting, which makes the car much slower.
In the beginning of the movie, when the baseball is thrown at Sean's car, it goes past him and lands on the passenger floorboard. In the next shot, the ball falls to the ground, with glass landing behind the rear tire, as if the ball had been thrown from inside the car.
During the first race between the Monte Carlo and Viper, the starter pulls off her bra and throws it in the air. It lands about 10 feet in front of the two cars. Both drivers shift gears, accelerate for a few seconds, then drive past the bra, which is now 100 to 200 feet from where it landed.
When Sean and Neela eat Japanese food on their first date, Neela puts the chopsticks in the box. When the camera focuses on Sean with Neela in the foreground, she is holding the chopsticks again. When the camera cuts back to Neela, the chopsticks are back in the box.
In the final moments of the last race between D.K. and Sean, the Fairlady Z sideswipes the Mustang and loses its passenger side light. D.K. drives up the side of the hill, where small trees and shrubs knock out the driver's headlight. In subsequent scenes, the driver's headlight is attached and working.
When Sean is first given the red Mitsubishi Lancer Evolution IX, his numerous collisions while practicing around the harbor tear off the rear spoiler. When he starts practicing on the hills, the EVO has no spoiler. When he first drives uphill, the spoiler is on the trunk. Subsequent shots show the EVO without the spoiler.
When Sean first drives with Han to get money from the "Paw" to collect money, the RX7 they drive in is a "left hand drive" car. When he is thrown out of the building and they decide to drive, the car becomes "right hand drive", and stays that way throughout the rest of the movie.
When Sean is walking past the cars before speaking with Neela in the parking garage, a golden Toyota Supra is behind him, on his right. When he looks to the left, a close-up shows the girl sitting on the Supra, to the right of the camera. In the next shot, he looks left, and the Supra is well behind him.
During the first race, in America, the Viper drives through a shadow of the house before Sean takes the shortcut between the houses. When the camera moves out and shows both cars from above, the shadow is gone.
When Han does donuts around the two women in the Mitsubishi, his car stops in such a way that if the women drove forward, they would hit the rear and side of his RX-7. In the next shot, his car is parallel to the Mitsubishi.
When Clay, driving the Viper in the opening race, swerves to ram Shaun's car, his car is slightly in front of Shaun's. In the next shot, from what would be Shaun's perspective, the Viper is clearly behind the other car.
If Twinkie was a military brat, his license plate would have a Japanese symbol that looks like a "Y" on the left side. Military members and their families with cars in Japan are required to have "Y" plates.
It's very unlikely for a Japanese high school student to own a car. Japan's driving age is 18, and the age of majority is 20. A high school student would need an adult signature to buy a car, or at least buy the mandatory insurance. Japanese teens who join motorcycle gangs, which are affiliated with organized crime, are often provided with stolen vehicles, which they generally drive without a license. The students depicted in the movie would appear to fit the bill. However, kids in motorcycle gangs usually leave school after ninth grade, the minimum leaving age in Japan, and rarely advance to high school.
Sean's father is credited as "Major Boswell." When he is in Naval uniform, his shoulder board clearly displays the two full stripes of a full Lieutenant, and the collar insignia, while improperly gold, also has the two bars of a Lieutenant. The rank of full Lieutenant in the Navy is O-3. Major, O-4 is used in the Marine Corps, Army, and Air Force. The Naval equivalent is Lieutenant Commander. Major is denoted by a gold oak leaf cluster, not twin silver bars. A Lieutenant Commander in the Navy also carries the gold oak leaf cluster on his collar, and the shoulder board carries two full strips and one half strip between.
Before Sean and Morimoto race, Han makes a bet with DK, putting up his 72 Skyline for the chance to receive DK's 86 Corolla. In the 1980s, the Corolla was called the Sprinter in Japan, and the 86 Corolla they talked about is a Sprinter Trueno. Only America and other export countries had Corollas.
If Sean doesn't speak Japanese, he would likely not go to a regular Japanese high school. American military kids can attend schools on base. He might attend a private international school, with Japanese and non-Japanese students.
Shortly after Twinkie's Volkswagen Touran "Hulkmobile" minivan is introduced, Shawn and Twinkie drive off. In the next scene, when the Touran enters the car park, a set of tires appear on its roof. In a deleted scene, Reiko and Earl steal tires from a gas station.
Twinkie appears to run a smuggling type operation, where he sells a wide range of goods (perhaps obtained cheaply on US bases). This is almost unheard of in Japan, where there is no shortage of legitimate retail outlets to purchase pretty much anything. Smuggled goods could be much cheaper than retail, since he presumably would not have to pay tariffs or charge sales tax.
When Sean, Neela, D.K., and Sean's dad meet after Han's accident, the camera is near the headlight of the Fairlady Z. Light circles appear for a few seconds, in the bottom right of the screen, where the lens of the camera caused distortion from the headlights.
When the baseball goes through Sean's car window, the driver puts the car in park. The shifter could be mounted on the steering wheel, but it's not clear. The car has a clutch during the race, yet the floor shifter is semi-automatic.
During the chase, Han is t-boned at an intersection. The car is hit near the rear end, then begins to slide around. When the angle changes, the car is hoisted in the air, and the left side of Han's car comes apart like a paper bag, even though he was hit on the right side.