Visible crew/equipment: During the scene where Ted and Dom are looking at Mary speaking with Warren and Tad from behind the tree, if you look carefully you can see the camera and crew in the reflection in Ted's glasses.

Continuity: In the confrontation scene where all of Mary's admirers are forcing her to choose between them, Woogie is sat on the couch with a pile of Mary's shoes. Every time the camera shoots back to him, you will notice that the position of the shoes changes each time. This is also mentioned by the directors on the DVD commentary.

Continuity: About one hour into this movie, when Healy is playing tag with the 'Neary group people' he goes for the touch down and Warren runs after him to get the ball. As Warren first dives for the ball, you can see that he has three red tags attached to his back, in the next shot as he lands you can see that the tags have disappeared.

Visible crew/equipment: When Mary is having lunch with her three friends and she is talking about the kind of guy she wants to meet, you can see the boom mic in the reflection of her sunglasses.

Continuity: This is during the scene on the outside steps of Mary's office, when Mary and Ted see each other for the first time. A suit-wearing businessman comes from the left side of the screen behind Mary twice. This happens when Mary is saying "Ted? Is...Is that you?" and the camera goes back and forth between Ted and Mary.

Continuity: When Pat is spying on Mary, the first morning he spies on her, Mary leaves her house and walks down to a deck and she throws Herb an apple. In a wide shot, on the barrel next to Herb is a cup, yet in the following closeup a bottle of whisky appears from nowhere.

Continuity: When Ben Stiller got his "frank and beans" caught in the zipper, the friendly police officer thought he would assist with the problem. He unbuttoned his sleeves and rolled them up, but then the next camera shot showed them buttoned up, and had to be rolled up again.

Factual error: The chiropractor that Ben Stiller's character visits says "Tender fascial tissue left of L7" as he is treating his back. However there are only 5 Lumbar Vertebra in our back, L7 doesn't exist.

Visible crew/equipment: When Mary, and Ted are driving with the dog on top of the car, when Ted opens the door you can see the camera operator, and the boom mic reflect from the car door.

Continuity: When Mary and Pat are at the carnival, her cotton candy shrinks faster than she is eating it.

Continuity: There is a scene where Ted and Mary are on a date and Mary is eating candy floss. There is a cut from her holding the candy floss where she and Ted talk and she doesn't eat any of it at all. Next shot showing the candy floss however, and there is a lot less than there was a couple of seconds before.

Revealing: When Puffy the dog bites Ted and pulls him along, Ted digs his fingermails into the floor, they scrape along, making marks. If you look very closely you can see faint pre-made marks made in the floor, where he drags his nails along.

Audio problem: When Mrs. Jenson see's Ted's thing caught in his zipper, she turns and yells "Holy Shit!" Her lips however don't reflect these heard words.

Continuity: When Mary says to Ted "I have a lot of fun with him" about Warren, her hair falls over her eye. In the next shot it is pushed back.

Continuity: When we see the first shot of the meeting Dom is holding, you can see the meeting table with loads of sheets on it. Then it changes to a shot of Dom standing by his big pad (just before Ted runs and yells "Mary's a fox!"), and the sheets on the table have moved around and some have vanished.

Continuity: When Pat is round Mary's, he is holding the dog. Between a wideshot and closeup, the way he holds the dog changes.

Factual error: Ben Stiller takes Cameron Diaz to the prom in 1985, but picks her up in a car made well after that; it has the newer-style headlamps.

Continuity: When Puffy the dog goes crazy, he bites Ted's neck and Ted crashes onto the counter, smashing into some wine glasses and cups. Between a closeup and a wideshot, the smashed glass that lays around Ted changes. Also in the closeup Ted is fully on the counter, yet in the wideshot he is half on the counter, with his legs hanging off of the side.

Continuity: When the dog is dead, Pat tries to revive it by using some wires. When it fails, he puts the wires on the couch then peeks into the kitchen to see what Mary and Magda are up to. Then in the next closeup of the dog, the wires how moved to laying on his stomach.

Continuity: In the scene where Ted is sitting on his bed, he pulls out his wallet to look at a picture of Mary. When he first pulls it out, he is looking at it from the side. But when they actually show you the face of the picture, it is upright.