When Sam and Andrew are in the bathtub, there is a small cup behind Sam. Later, when she gets up to get a cup to catch Andrew's tear, the cup behind her has disappeared and she puts the new cup where the "ghost" cup was.
In the first shot of the phone in Andrew's bedroom, the antennas are down. In the next (wide) shot, they are both up.
When the girl is on Andrew's lap at the party, his friend Mark has a cigarette in his hand in the background, but it disappears in the next shot.
In the pool scene when everyone (except for Andrew) jumps into the pool, everyone emerges from the water during the wide shot, including Sam. However, on the next close-up of Sam it shows her still underwater, before submerging.
When Andrew goes into his father's bedroom and wakes him up to talk, his father puts on his glasses. In the next shot, his glasses are back on top of the newspaper.
In the opening credits, after "Fox Searchlight Pictures and Miramax Films Present", the screen reads "Camelot Pictures Presents". It should read either "In Association with Camelot Pictures" or "A Camelot Pictures Production" Camelot Pictures is a production company, not a film distributor.
When Andrew lies in bed the morning after the party, sunlight is supposedly beaming through holes in the curtains. However the light beams are at varying angles obviously from several light sources.
Obvious dummy baby in the opening shot on the airplane.
When Sam's mom gets the Dobermans off of Andrew, we still hear them barking, even though their mouths are not moving.
When Largeman walks into the bathroom you can see behind him
that the bedroom has no ceiling, and lights are visible.
You can see the reflection of a light in the water on the crane during the screaming scene. It is a very cloudy/stormy day, this would not have been visible otherwise.
When Andrew is still in L.A., he opens the mirror and a camera is reflected in it.
When Diego is in the hallway at the motel, some of the production crew are reflected in one of the mirrors in the top right of one of the shots.
In the opening scene with Andrew in his L.A. bedroom, a gobo head (light stand) is reflected in the top of the fan blades.
The closing credits thank "The Township of Morristown". No such municipality exists. There are the "Town of Morristown" and the "Township of Morris". Which was intended is not clear.
In the restaurant scene near the beginning, when the snotty customer asks for bread, Andrew Largeman replies they have none and explains this is because it is a Vietnamese restaurant. In fact, because of the French colonization of Vietnam in the mid 19th Century, French baguettes are a common staple in Vietnamese cuisine and any good Vietnamese restaurant would most likely have them in their kitchen.
At a Jewish funeral, the casket would be lowered completely into the ground. The first shovel full of dirt would be lifted with the shovel head upside down to show reluctance to fulfill the mitzvah of burying the dead. After the first throw of dirt, the shovel is turned right side up and used. Then it is passed to others and the family and friends do most of the refilling. When Andrew's father is putting the dirt on the casket it is above ground and he has the shovel right side up.
After Andrew is pulled over while riding his motorcycle, his cop friend pulls his sidearm and shows Andrew where the safety is. He is holding a glock pistol which has no external safety.
When Largemen first enters his father's office after the funeral to talk about his headaches, his father's glasses alternate locations on the desk. In some shots they are open on the table, in others they are not on the desk at all.
About 10 minutes into the film, when Andrew Largeman is riding a motorcycle without head (helmet) or eye (goggle/glasses) protection, he is stopped by a Police Officer for speeding (only). New Jersey has both helmet and eye protection laws.