In 1978, Dirk Diggler buys a brand-new Corvette with Goodyear Eagle ST tires. Goodyear introduced the Eagle line of tires in the early 1980s. The ST was never an original equipment tire, it was available only as an after-market purchase.
When the three guys discuss a drug deal with Rahad (set in at least 1984, based on the songs "Sister Christian" and "99 Luftballons" from that year), the audio mix tape runs out the moment the song currently playing reaches its climax, before reverse-side playback. A close-up shows a Maxell 'clear style' tape, not an early-80's style.
When Amber and her ex-husband met with a judge about custody
in September of 1983, portraits of President Ronald Reagan and Governor Jerry Brown are on the wall. Brown was governor from January 1975 to January 1983; George Deukmejian had been governor for several months by September 1983.
In the finale, when Rodriguez and his brothers unveil their new club sign and see that it's misspelled -several 1990s car are parked off to the right side of the screen. This scene is supposed to take place in 1984.
Just after the scene in which Dirk Diggler is acting on the film set for the first time (with Amber Waves), there is a brief take in which a turntable plays a record. The turntable stylus and cartridge follow the "P-mount" standard, also known as "T4P", a technology that Technics invented in 1980 and which was adopted by other manufacturers. Yet, the scene happens in the late '70s, when such standard did not exist yet.
When Rahad is explaining that he likes to make mix tapes, he asks Cosmo which one they're listening to right now. They both agree that it's #11. The tape runs out, and when the camera shows a closeup of the tape auto-reversing, it's clearly labeled #6.
(around 1:09:45) During the New Years Eve scene, Todd Parker can be clearly scene walking directly in front of the couple having a discussion at the table, holding a beer and without his jacket socializing like he's been there awhile. Fast forward to 1:12:00, Todd enters the scene and recognizes Reed and they start talking, and it's obvious that he had just arrived, wearing a different shirt and a jacket.
Before entering Rahad's house, Todd places a large handgun in his front waistband. It is clearly visible later as he first approaches Rahad to give him a hug. The gun disappears until he finally brandishes it.
During the pool party scene, the underwater swimming girl gets up. The camera pans as she passes, and the dark reflection of the cameraman holding the underwater camera is visible in the sliding glass door.
The 1977 Corvette is described as being a car with a 350 cubic inch engine producing 325 hp, a 4.10:1 rear end gearing, having a 4 speed manual and an aftermarket intake manifold. This is not true. As this is a California car, it had the de-tuned L82 California emissions engine. This engine produced a mere 165 hp and is actually the least powerful factory V8 engine put in a Corvette. Even with a good aftermarket intake, this thing would not be close to 325 hp. It would need new cylinder heads, a new camshaft and a new carburetor to make even close to 325 hp.
The divorce/child custody hearing of Amber Waves in 1983 clearly took place in front of a California State judge. The California state seal is also depicted. These sort of cases are routinely a state matter. Yet the state judge's conference room still had huge portraits of Ronald Reagan and George Bush on the wall.
When Little Bill complains to the cinematographer about his wife having sex with other men, he says, "My fucking wife's on the driveway with a fucking ass in her cock." Little Bill was supposed to say "My fucking wife's on the driveway with a fucking COCK in her ASS", but the director loved the way the incorrect line showed how angry and flustered Bill was, and left the scene intact.