Revealing mistake: When Igby and his brother are removing the plastic bag from Mimi's head, her eyes blink.
Continuity mistake: When Igby's dad breaks the shower door, he breaks it with his right arm. The next shot has him cradling a badly cut and lacerated left arm.
Continuity mistake: When the spoon falls, 2 globs of the strawberry flavoured poison land on the carpet beside it. When the spoon is seen later, the poison is gone. (00:03:05 - 01:30:10)
Continuity mistake: When Igby is in the restaurant with his mother, there is a olive bowl on the table. It changes place between shots.
Continuity mistake: When Igby is saying goodbye to Oliver at the end of the movie, Oliver's glass keeps changing hands.
Continuity mistake: When Rachel is beating Igby, his coat fall near a pillar. It keeps disappearing and changing places.
Continuity mistake: When Igby puts Rachel in the bath, she changes place between shots.
Continuity mistake: In the cafe when Mimi is talking to Igby, the amount of white wine in her glass changes from shot to shot.
Continuity mistake: When Igby is saying goodbye to Ollie, Igby's collar is alternately neatly down and crumpled up. (01:31:45)
Continuity mistake: During the party, when Oliver puts Igby's cigarette in his glass, its length is not always the same.
Continuity mistake: When Igby is at his Godfather's party, and is drinking from the wine glass with cigarette ash in it, the glass changes hands. When the ash is put into the glass, he is holding it in his right hand, then the camera angle changes and it is now in his left hand, where it remains for the rest of the scene.
Continuity mistake: When Sookie and Igby are in the diner, in some shots the straw in Igby's coke is straight and in others it is bent over at the top. (00:41:05)
Continuity mistake: When Igby is throwing water-filled balloons off of the building, the shadows of the people on the ground are pointing in a completely different direction to Igby's shadow on the roof. If it is the same building, then the shots were taken several hours apart. (00:49:10)
Continuity mistake: In the hospital, when Igby and D.H. leave Russel, they go in a different direction depending on the camera angle.
Continuity mistake: When Igby and Sookie are in the dinner, the cherries in her sundae keep changing position.
Continuity mistake: In the death scene at the beginning, a spoon drops to the floor when the mother dies. At the end of the movie, in the return to the death scene, the older son is feeding the mother the poison and then sets the bowl and spoon aside. The mother never has the spoon in her own hand.
Continuity mistake: When Igby and Sooki are eating ice cream near the end of the film, the amount of ice cream on Sooki's spoon changes throughout.
Continuity mistake: When Igby is saying goodbye to Ollie, Ollie's drink is alternately being held next to his stomach and down by his side. (01:31:45)
Continuity mistake: When Jason and the children are walking along the street, talking about his illness, a red car appears parked behind them. (00:04:15)
Continuity mistake: There is a scene when Igby knocks at Sooki's door. From her side, there is a "magic eye", but on the outside, there is nothing. (01:09:00)