Continuity mistake: In the scene where Shaun is talking to his Mom in her bedroom before the man on the Stanford board comes over Shaun's Mom takes the same pillow off the bed three separate times. In each shot where it cuts to Shaun then back to his Mom she takes the pillow off the bed.
Factual error: In the scene where it shows the April calendar, right at the beginning, it shows 31 days in April. There are only 30 days in April.
Continuity mistake: When Sean is in the college counsellor's office he gets mad and grabs her from across her desk, suddenly they are at the side of her desk where she knees him in the balls.
Continuity mistake: During the fire scene, when the cop is putting the Dean in the patrol car, Hanks puts one hand on the open door, and the other on the roof of the car. In the next scene, he walks up to the window.
Factual error: At the end when Shaun says, "I'm goin' surfing," when the shot shows the ocean as he runs towards it, there are no waves to surf on.
Continuity mistake: When Shuan is at the party where he spies on his girlfriend, he is talking to a girl that leaves him because she has to do "the dance" with her friends. The sofa he sits down on changes from this shot to the next shot we see of him.
Continuity mistake: The film is set in April, yet when Sean arrives at Stanford the red and yellow foliage on the trees indicates that those scenes were shot in the autumn.
Continuity mistake: When Lance is reading Shaun's transcript he pukes on it. But as the scene continues, some of the puke disappears from the page, then further along it re-appears.
Continuity mistake: During the scene in which Colin Hanks finally meets the writer played by Kevin Kline, Hanks' hairstyle is vastly different than it was just moments before as they were talking outside. After Hanks leaves and goes back outside, the hairstyle has changed back to what it had been before.
Continuity mistake: When the little boy cries about the milk when they show him the glass is full but in the next shot the glass is almost empty.
Continuity mistake: When Sean is arguing with the lady about his transcript he comes right up to the desk and is very close to her face. In the next shot he tells her she's a moron and he's in a corner in the back of the room.
Continuity mistake: In the part where Sean is upstairs in the mother's room, and they are arguing, she is taking pillows off the bed. Every time the camera goes back to her, she keeps on taking off the same pillows.