Continuity mistake: At the very end of the movie when Ferris' mom is tucking him into bed the blanket is showing the line at the top then folded in and back several times.
Continuity mistake: In the parade scene where Cameron and Sloane rush out attempting to get Ferris of the float, they are approached by a police officer wearing a black jacket. Seconds later there is an aerial shot of the parade, and C and S are being led back to the kerb by a police officer who has no black jacket.
Continuity mistake: Notice Jeanie's watch at the police station, and how it changes by hours during the short scene with Charlie Sheen.
Continuity mistake: Right at the end, as the Ferrari is flying out into the trees, it lands in the middle of a couple of very large maple trees. In the next shot, when the kids are standing looking down at the car, it is in a clearing, with nothing around it. It is unlikely that the trees were completely pulverized by the car and it was landing directly on top of them so it did not continue to move away after the fact.
Continuity mistake: When Ferris turns off the shower, the steam disappears in the close-up angle, only to reappear half a second later.
Factual error: Cameron tries to stop Ferris from borrowing his father's red sports car, explaining that it's an extremely rare and valuable '61 Ferrari 250 GT California. But the car itself is not a real Ferrari. It was manufactured by Modena Design and Development of El Cajon, California, and is a "Modena GT250" which strongly resembles the 1961 Ferrari 250 GT California Spyder. Since the film makers were throwing the car out of a window, using a real Ferrari was 'cost-prohibitive'. Comparing the real Ferrari to the Modena, differences include the Modena's sharper body crease above the grille, the more steeply angled headlamp covers, higher-mounted emblem and counter-sunk hood scoop.
Continuity mistake: When Ferris calls Cameron, the mess by his phone changes between angles.
Continuity mistake: In the scene where Ferris is talking on the phone with the freshmen and playing his "sick sounds" on the keyboard, his legs cross and uncross several times between shots.
Continuity mistake: When Rooney first arrives at the Bueller house, he parks in the street by the fire hydrant with a good deal of room between the car and the curb, however when the policeman is putting the ticket on his car, he is right up next to the curb.
Continuity mistake: When Jeanie and Charlie Sheen are talking on the couch in the police station, Jeanie's legs go from crossed left over right to right over left and her arm goes from resting on the couch to by her side and back again.
Continuity mistake: Sloan's hairstyle changes from parted to the side, to the left and straight back throughout the scene in which she says goodbye to Ferris.
Factual error: The odometer only goes up by 10 miles between the time Cameron freaks out and when they're back in the garage, but when Cameron freaks out they're at a famous Chicago lighthouse that is 1/2 hour outside the city, more than 10 miles, so the odometer should have increased by a larger distance.
Continuity mistake: In the scene where Ferris is singing "Twist and Shout," you can see a building sign that reads '33 North Dearborn Street.' After the shot cuts, you can see an intersection of two streets: Adams Street and Dearborn Street. The address '33 North Dearborn Street' is a few blocks away from the intersection.
Continuity mistake: When Rooney gets on the school bus, he crosses a grass boulevard with no sidewalk to board it. The bus never moves. When the bus pulls away, there is a sidewalk next to the bus where the grass was.
Continuity mistake: In the scene where Ferris catches the foul ball, the television shows the stands where Ferris & company are sitting (down the left field line) as being in the shade. When the television shows the close-up of Ferris catching the ball, he is in the sun. When they have the actual shot in Wrigley Field, it is overcast.
Continuity mistake: Cameron's shirt with the The American Medical Association's symbol changes half way through the movie. You can see how they try to cover it up by turning it inside out, but it still shows.
Continuity mistake: When Ferris talks to Cameron and plays with the mouse, the keyboard comes closer to the edge of the table between shots.
Continuity mistake: Ferris is messing with the equalizer on his stereo system (the one that plays the snoring), while he's talking to the camera. Watch the levels on the equalizer, they change from the close-up and back to normal in the wide shot.
Continuity mistake: Whilst Jeanie and the guy in the police station are talking, a man in a suit walks behind them and then takes a file from the woman at the desk. However, without walking behind either of them, he ends up on the other side of the room.
Continuity mistake: When Jeanie says 'I don't know why I'm here', there's no one behind her. However, in the next shot of her, about a second an a half later, there are three people behind her.
Answer: Cameron stares specifically at the child in the painting, because he identifies with it. He feels the lack of affection and attention from his own family (unlike the child in the painting who is enjoying time with her family, the mother is holding her hand).
Shipper