(at around 40 mins) Matt throws his raggy cloth at the oncoming car's windscreen. It misses and hits the top of the car's side window. In the next shot, the cloth is firmly across the whole bottom half of the car's front windscreen.
The window goes from closed to open to closed to open after Melinda is told to open it during the fight at the Barlow party.
A blue and white 1962 Chevrolet is seen just before the wreck and then seen again behind the red and white 1957 Ford during the wreck.
Jack's induction notice says he is to serve in the United States Marine Corps. When he comes home from Vietnam he is an Army Airborne Ranger.
During the scenes set during the 1960's, almost all of the male extras in the film have 1970's hairstyles (long or afro) or have 70's style facial hair (handle bar mustaches and beards) that were not in style during the time.
The women are wearing more modern 1970's style swimsuits that didn't exist in the 1960's.
Almost all of the clothing in the film is from the 1970's and were not in style back in the early 1960's.
When the guys are driving to the Star Burger Cafe the first time in 1962, a green mid-'70s Chevy van is headed south, behind a blue mid '70s Dodge van. As they pull into the parking lot, a couple of mid '70s foreign imports and a green '68 Mustang hardtop drive south. None of these would have been around in the early '60s that this is.
When Matt drives his 1959 El Camino to the Cosmic Cafe in 1968, a 1970s Dodge van and Chevrolet van are see going southbound, along with a 1970s Firebird. A Ford Maverick and a 1973 Chevrolet Impala are parked on the side. Other 1970s cars are seen.
At 1:37:55, when the shot fades into the sun half above the horizon on the morning of "Big Wednesday", that shot is showing the sun setting into the ocean - as it does on the West Coast - so it is a sunset, not a sunrise.
During the party scene a girl screams "Waxer, no!" when another character, Crusher, not Waxer, attacks her.