Continuity mistake: The rear view mirror disappears when Jeanie is speeding home.
Continuity mistake: When Jeanie meets the boy at the police station, his hair changes after every cut from her to him.
Continuity mistake: In the scene where Ferris' mom comes home to check on him to make sure he's really home sick, when she's walking down the hall to enter his room you can see the door knob is a gold/old looking one. When she goes to turn the knob and go into the room, they zoom in on it and it's a crystal door knob.
Continuity mistake: Cameron kicks and shatters the glass light on the front of the Ferrari towards the end of the movie. A shot of the entire garage is then shown and there is no glass on the floor.
Continuity mistake: When Ferris is talking with Cameron on the phone and playing on the computer, there is no Pepsi can on his desk. A second later one appears next to his hand. The can then disappears in the next shot.
Continuity mistake: When Mr. Rooney goes to Ferris's house he is wearing a long sleeved shirt and coat jacket. A shot of his arm ringing the doorbell shows a bare arm with dark hair. When they return back to a shot of Mr. Rooney, his sleeve is touching his wrist and he does not have dark hair on the back of his hand.
Continuity mistake: When driving home from the city there is obviously a fake backdrop to simulate a moving car. The car can be seen to change lanes but Ferris never actually turns the wheel of the car.
Continuity mistake: When the Ferrari goes through the window and the three of them are standing there, you can see the camera tape on the floor where they are supposed to stand. Also the broken glass on the window changes a bit over the course of that scene.
Continuity mistake: At the end, Jeanie slams the kitchen door in Mr Rooney's face. Watch the pane of glass in the door. In all previous exterior views of the door, the pane is composed of about 4 horizontal pieces of glass. It is apparently a "jalousie" window that opens like a venetian blind, so there are no mouldings between each piece of glass. However, as soon as we see the inside of the door behind Jeanie, visible through the curtain is the silhouette of a "criss-cross" moulding grid, dividing the window into 9 panes of glass.
Continuity mistake: When Ferris and Sloane are in the pool, the Pepsi can behind Ferris changes position in different shots.
Continuity mistake: When Ferris, Sloan, and Cameron go to the Sears Tower they lean their heads on three separate windows. Ferris's window is the same as Cameron's. You can tell this when you see them look at the top and top right.
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.
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.
Answer: Sloane knew it was a hoax. Ferris would not have done something like that without her knowing. Rooney pretty much had figured it out, but could never prove anything. Once he was discovered inside the Bueller house (illegally) by Ferris' sister, anything he did know he would have to keep to himself.
raywest ★
Sloane starts to put her jacket on the moment that she sees the school nurse walk into the classroom, suggesting that Sloane already knew she would be called out, and she smiles to her classmates.