When Matt is trying to tell Jenny he wants to break up with her, and she stabs the cutting board with a knife, the knife makes a shuddering "twang" sound, which is impossible because she is still gripping the handle of the knife.
In the very beginning when the two criminals are escaping, there's an aerial shot of the getaway car. In this shot, we see that there are no cars in the vicinity of the car. A few seconds later when we see a shot inside of the car, we can see through the rear window that there are many cars surrounding the car.
The shape and amount of damage caused by Jenny banging the bed against the wall changes between shots - at first it's L-shaped and makes an actual hole in the wall. Once she stops, it's just a straight line and just surface damage.
The length of Hannah's skirt changes between the close-up and the far shot of when Matt is staring at her bottom while she is standing on that step ladder. The length changes again to shorter when she descends from the step ladder.
In the very beginning of the movie when the robbers get in the Lincoln, they cut off a brown SUV causing it to be sideways in the street behind them. In the very next scene we see them pass the exact same SUV.
When Matt and Jenny walk into the art gallery on their date, Jenny is wearing heels that are pointy and you can hear her steps on the wood floor. A few shots later you catch a glimpse of Jenny taking a step in black ballet flats. And as she walks along the gallery you no longer hear her footsteps.
When Matt is hanging from the torch on the Statue of Liberty, as the rope first starts slipping the camera zooms out to show the rope is tied around his right foot. When the knot comes loose and Matt begins to fall, the camera zooms out again and shows the rope tied around his left foot.
In Hannah's apartment, immediately after the shark crashes through the window, Hannah runs into the room wearing mini-boots with fur around the tops. When the camera cuts to the next shot showing her feet, she is wearing fur slippers.
In the scene when Matt is breaking up with Jenny, she blows him against the wall. When he hits the wall a basket falls behind pinned to the wall by his body. In the next shot, the basket is now lying next to him on the floor. In the subsequent shots the basket disappears and reappears in different positions next to the upside down table.
Matt brings Jenny to his house and they are getting undressed, and Jenny opens her shirt to the G girl costume underneath, and Jenny runs into the bathroom to quickly change. Her silk shirt goes back and forth between short and long, the long version has a matching silk tie belt, and short version has no belt.
In the second shot of Jenny hitting the refrigerator door with her head as Saunders is breaking up with her, she obviously causes no damage to the door (the door panel has been pre-bent) and she causes no more damage as she continues to hit her head against it.
In the flashback in which we see the meteor land, the trajectory of the meteor implies a landing point many miles into western New Jersey (the Manhattan skyline is visible in the same shot). Barry and Jenny, on the eastern shore of New Jersey, are the first people to reach the meteor, which is absurd.
In the early scene during which Matt and Vaughn are discussing the super power Vaughn would most like to have, they are clearly on a yellow-line R subway train. This is confirmed a short time later, when Matt chases a robber out of the train and they run up a staircase that says "uptown N R W". When they run out of the station, however, they run out of the red-line Franklin Street 1 train station. This is impossible, as the 1 train does not intersect with the R train, or any other train line, at this stop.
At the beginning of the movie, when G-Girl foils the robbery getaway and the crooks shoot at her, the bullets supposedly bounce off her body and fall to the sidewalk. Actually, the bullets have clearly never been shot and are not even deformed, as they would have been if they had bounced off her. Also, if the bullets had ricocheted off her as they are supposed to have done, they would not fall in a neat pile at her feet.
As the film opens, there's a shot from the back seat of the escape car looking forward. If you look at the dashboard, you can see the transmission gear selector is in park, even though the car's moving.
The goof items below may give away important plot points.
In the closing scene, where Hannah offers her help to Jenny (G-girl), Hannah extends her fist towards Jenny for a fist-hit. At this point, Hannah is wearing black gloves. When Jenny and Hannah actually touch fists, Hannah's glove is off. Moments later, the glove is back on again.
When G-girl breaks into Matt's apartment towards the end, after his car is stolen, she is wearing a diagonally striped sweatshirt and her hair is crimped. But the hood is either on or off depending on the shot. It is up when the camera is behind her, but down when the shot is over his shoulder.
In Matt's apartment, there is a window above his bed. You can
see daylight shine through throughout the movie. At the end, when Matt and Hannah are having sex and breaks through the wall, they enter another person's apartment. There wouldn't be a window connecting to each other's rooms.