Continuity: 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.
Continuity: Nicky sideswipes several parked cars with her maroon PT Cruiser. The passenger side mirror gets taken out, but can still be seen a few shots later.
Factual errors: 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.
Audio/visual unsynchronized: 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".
Continuity: 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.
Continuity: 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.
Continuity: 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.
Continuity: 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.
Continuity: When Andy is doing magic for Trish's daughter, his sleeves go back and forth between being rolled up to his elbow and being pulled out normally.
Continuity: When outside Andy's place of work, there are many bare deciduous trees indicating winter. When entering the store, there are numerous signs that state "Summer Sale"
Continuity: The red Saturn is in different parking spaces between shots the first time Andy enters Trish's store.
Continuity: The brochures on the table at the health clinic change position between shots.
Continuity: When Andy and Trish are in bed on the night of their first date, the quilt lying on top of the covers changes position between shots
Continuity: 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.
Continuity: When Andy is making waffles, he opens the lid to take them out. In the next shot, the waffle maker is closed.
Continuity: In the argument between Andy and Trish (before she runs off and he chases her on his bike) a red action figure on the shelf changes position several times.
Continuity: Cal's sideburns are not consistent, especially in the Date-O-Rama scene.
Crew or equipment visible: When Andy is at the speed dating, where the girl in the pink top's breast pops out you can clearly see a hand pulling at the bottom of her top pulling the neck down and making it pop out.
Continuity: In one of the deleted scenes, Andy is shown getting out of the car after the drunk girl has thrown up on him. However, no vomit is visible anywhere on his clothes.
Continuity: When Andy asks his friends to tape Survivor, Trish turns to walk away and when they drop to a long distance shot Andy is in front of Trish.
Continuity: When Cal is telling the Tijuana story to Andy, his arms are up in some shots and down in others.
Audio/visual unsynchronized: 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.
Factual errors: When Dawn of the Dead (2004) is being played on the TV sets, it is being played out of sequence.
Continuity: In the poker playing scene, Andy wins with a Full House and rakes the pot in. The next shot of Gerry yelling and leaving, the chips are visible back in the center of the table.
Continuity: 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.
Miscellaneous: 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.
Continuity: When Andy chats with Trish at the "We Sell It on eBay" the lamp illuminating Trish's face changes positions.
Miscellaneous: When Cal is telling Andy the horse story in the back room at Smart Tech in the beginning of the movie, you can see Radio Shack brand batteries hanging on the wall behind Andy.
Continuity: 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.
Continuity: 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.
Continuity: 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.
Continuity: After the waxing scene, only Andy's right nipple has been waxed. In the scene when he's at Beth's house, both of his nipples are waxed.
Factual errors: 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.
Continuity: When Paul Rudd's character, David, is asking Andy if he wants to play poker, his hands alternate between by his side and in his pockets.
Continuity: 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.
Crew or equipment visible: When Cal and David are playing video games at Andy's apartment, the camera shows the television screen dead on in some shots. During these shots, the crew's reflection can be seen on the screen.
Factual errors: The SmarTech store where Andy works has factual error in the store hours information: Mon-Fri: 10am-9pm Fri-Sat:10am-10pm Sun: 11am-7pm. According to them Fri closes at 9pm and also at 10pm.
Continuity: 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.
Errors made by characters (possibly deliberate errors by the filmmakers): When Andy is talking to the large chested girl from Minnesota, Andy remarks, "the land of 1,000 lakes". The actual motto is "the land of 10,000 lakes". This may be an intentional mistake.
Continuity: When David and Amy are speed-dating, the lime moves around Amy's glass in several shots.
Errors made by characters (possibly deliberate errors by the filmmakers): In the Japanese restaurant the waitresses are asked to sing 'happy birthday' which they sing in Japanese. However, they sing to the tune of 'if you're happy and you know it ...' which is not the same tune as 'happy birthday to you.'
Continuity: When Amy comes to David's table during the speed dating scene, she sits down twice.
Continuity: Andy's waxed chest patches remain hairless even after "20 dates".
Continuity: When Andy gets in bed and goes to sleep his blanket is one color. When he wakes up the next morning it's a different color.
Continuity: Andy's chest is still waxed the night he's in Beth's apartment, which is the same night he tells Trish he's a virgin. But by the time they first have sex, his hair has grown back - unlikely that they would have waited that long.
Continuity: When the drunk girl 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.