Just before the second time Andy calls Trish and claims to be a telemarketer, there is a shot of the front of his apartment, and chained to the railing is the nice new red mountain bike that Trish buys for Andy much later in the movie.
In the Theatrical release, When Andy and Cal carry the woman's television to her vehicle, they don't drop it (they did in the extended scene on the unrated DVD), yet when they place it into her vehicle you can still hear the tinkle of glass from where they dropped it in the extended scene.
On the Michael McDonald "Soundstage" DVD, the song "Take Me In
Your Arms" is being played in the background on the store entertainment system, and shows clips of Tom Johnston singing along and playing the tambourine; on the DVD, Johnston plays guitar and sings lead vocals on "Take Me In Your Arms".
David complains to Paula about her playing the Michael McDonald Soundstage DVD constantly on the store entertainment system, and also adds in being tired of hearing the song "Ya Mo Be There". The song is not featured on the DVD.
In the consummation scene at the end of the movie, when Andy is shown after the 1 minute marker, his chest hair is still very spotty and thick. However after two hours of apparently exhausting sex, he rolls off and his chest hair is nice and even, almost as if brushed that way.
The second time Andy goes to work, as he shuts the door, a black SUV is reflected in the door as it closes. When we see the outside of the door from the inside of the store, there is only a railing, no SUV.
When Andy and Trish are in bed after their first date she takes off her blouse and tosses it over Andy's side of the bed and it slides down onto the floor. In the next wide shot the blouse is lying on the comforter to Andy's right. When it cuts back to the closer shot the blouse is gone again.
As Trish is driving away in her car and Andy is chasing her on his bike, he veers down a street to the left in hopes of cutting her off. When he reappears to cut her off he crashes into the "passenger" side of her car not the driver side.
Towards the beginning when David is chasing Andy outside and apologizing for everyone teasing Andy about being a virgin, Andy runs to the back door of Smart Tech but it's locked. When Haziz comes out to smoke and talks to David then gets insulted by him and goes back inside, Haziz opens the back door with no problem.
After Andy leaves his house in the beginning, he first rides his bike past the blue Ford Bronco. Then, when he joyfully swerves on the street, he's going the opposite direction, away from the blue Ford Bronco.
When Andy and his co-worker friends are out on the loading dock busting the fluorescent bulbs, there is a white mark from a busted bulb on the dock next to Cal. Later when Cal busts the bulb on the dock, the mark appears for the first time.
After Andy rolls off the bed in the 20th date scene, the shot cuts to Trish standing up. At this point, two of the action figure boxes on the bed in front of her are showing their labels to the camera : one says 'X-Men' and the other says 'Dracula'. In a subsequent shot of Trish shouting at Andy, the Dracula box has been moved and the label on the box can no longer be seen.
When Cal asks Andy if a doll on a shelf is Oscar Goldman, there is a Captain Action Doll next to Goldman, wearing his cap. The next shot is a close up of the dolls and Captain Action is cap-less. In the next shot, the cap is back.
Before Andy calls Trish the new bike is seen locked outside his apartment and when David is leaving and shouts, "I don't want your big box of porn, Andy," his old bike is shown locked to the fence now.
In the scene before Trish and Andy's argument, she is shown with her left arm around Andy's neck and her right hand on his collar. The camera switches to a frontal of Andy where Trish's hand is not on his collar, then switches back to show that it is.
When Andy is getting his chest waxed, after the first 4 wax strips, there are a couple shots of just his head while you hear a wax strip being pulled and then he yells. But when it shows his chest, no more hair is removed then before.
When Trish was writing her home phone number on the business card she gave Andy, she is initially shown writing her number across the top of the card, but in later scenes when you see the actual card, her phone number is written towards the bottom.
Before Andy goes to talk to Cal, the first verse of the song "Minute By Minute", is being sung by Michael McDonald on the concert DVD that is constantly being played on the store entertainment system. Right before Andy gets done talking with Cal in the back room, the same verse is being sung again.
At the sex ed place, Andy plays with the vagina model, the pieces of which fall apart. In trying to put them back together, Andy holds one of the pieces under his chin. In a subsequent shot, it's gone.
Early in the movie Andy gets a "partial" chest hair wax, and ends up with four bald spots on his chest. At the end of the movie, when he finally has sex for the first time, his chest is completely covered in hair again.
When Andy is walking down the street looking at women's breasts, he walks with the bus with the ''Eruption'' advertisement on it. When he crosses the road, just before passing the dogs, the crew's legs are visible in the window of the main door of the bus.
When Cal and David are playing a video game in Andy's apartment, Cal is using a Nintendo 64 controller. However the game they are playing is Mortal Kombat: Deception, a game that was released on the Xbox, Gamecube and Playstation 2, not the Nintendo 64.
When the blonde girl asks about the difference between Hi8 and digital videotape, she is holding a package of Hi8 tapes and a package of regular (non-digital) VHS tapes. Even if they were digital VHS tapes (D-VHS), she would have needed a special VCR to make digital recordings.
When Trish rushes back to Andy's apartment for forgiveness, she is able to get it even Andy is not home. Nowhere at any point in the movie do we see Andy give Trish a key to let herself in. When Andy arrives home he is seen unlocking the door with a key so there is no way Trish would be able to let herself in as she did.
When Nicky is side-swiping parked cars in her PT Cruiser, Andy's face inside the car shows trepidation as he screams. However, when the shot switches to outside the car, showing it swerving and hitting things, the stunt double's face is expressionless, almost bored.
The goof item below may give away important plot points.
When Andy crashes through the truck and lands on the street, Trish comes over. When they switch between the two during the conversation, Andy's head is on top of the yellow marker or his head is right below it, in several shots.