When Mule attacks Eli at the convention, Eli forgets to take his jacket off of the couch arm, and leaves it there. Several scenes later in Matt's bedroom, he is seen wearing the same jacket that he left behind.
All exterior shots of the limo show it to be dry, yet all the interior shots have the windows looking wet.
When Matthew is running naked down the street alongside Danielle's car, the interior shots from the car show that the window is open. As Matthew opens the door to finally get in the window is closed.
When Eli and Klitz are being chased by Mule, Eli jumps off the Balcony and jumps feet first. Somehow he lands face down on the titty cake.
In the strip club, Kelly orders a Scotch on the Rocks for himself and Danielle, whilst Matt orders a Long Island Ice Tea. When the waiter comes over there are 3 identical drinks.
Kelly could've got into serious trouble and went to jail for stealing money from Matthew's bank account. Even such as committing fraud. Matthew wouldn't be the one going to jail since he didn't commit fraud.
The music that plays when Matthew opens the door to reveal Danielle ready to accompany him to the prom is not "Hootchie Cootchie Man" as credited in the soundtrack listing and end credits, but is actually "Mannish Boy".
Kelly could've got arrested for barging into the school and kidnapping Matthew. Also the teachers should have reported this to the police and let Matthew's parents know.
In the strip cub, Kelly gives Matthew a cigar and then shows him how to light it. But he never cuts the cigar. He would not have been able to light it without cutting it first.
When Matt receives the acceptance letter from Georgetown, it appears to be a "thin" package that would signify a single rejection letter, rather than the more traditional "thick" package that signifies acceptance and contains all the materials needed.
Obvious body double for Matthew when he runs down the neighborhood naked.
When Matt receives the acceptance letter from Georgetown University, there is no state and no zip code present in the destination address.
In the first couple shots of the film where the characters are stating what they will always remember, one says that he will always remember Lacrosse champions. If you watch very closely, when he tackles the last man before the shot is over, the lacrosse ball clearly flies out of the net, but he is still running.
Danielle's car has blue background/gold lettered California license plates. California stopped making the blue/gold plates in the early 1980s. Her new style Beetle has to be a 1998 or newer. The only way a car that new can have the blue/gold plates is if they are personalized plates which go with the owner. The plates on Danielle's car are not personalized with a special word.
No one in 1974 (the date of the sex-ed film) was talking about "unprotected sex". That phrase came into vogue during the 1980s AIDS crisis.
When Danielle, Matthew and Kelly are in the strip joint Kelly lights the lighter without the distinctive sound of striking as heard on earlier occasions.
When Matt is dragged out of class at the end of the movie, his microphone is visible on his belt loop.
When doing the sex scene, Matthew's skin colored boxers are visible in several shots. Once from behind him up close. And twice from the front at a distance.
At the scholarship dinner, Matthew is with Danielle talking to a couple. When Matthew takes an interest in the man's tie, it zooms into Matthew's face. You can see that there is a microphone attached to the back of Danielle's hair.
The camera truck is reflected in the windows of the house across the street as Matt walks past with the inner tube.
When Kelly drags Matthew from class Matthew's microphone is visible on his back pocket as he is dragged to the door.
When driving to the porn convention in Las Vegas, Klitz is on the phone with his father telling him that they can watch Shark Week together another night. Shark Week is on in early august, well before they would have started school.