Continuity mistake: After Ferris plays with the synthesizer, the principal is fidgeting with some pages. The way they're folded changes between angles.
Continuity mistake: When the movie starts and Ferris' parents leave the room, his right arm swaps from being over the blanket to under, between frames.
Continuity mistake: When the opening credits are rolling, Jenny shows up in the bedroom and Ferris's hair keeps swapping from messy to brushed back and forth.
Continuity mistake: After the pinball girl shoots Pepsi through a straw at Rooney, he goes over to the counter and grabs some napkins to dry off, however, you can hardly see the wet spots, until the last shot - and then they are much darker.
Visible crew/equipment: In the scenes where Sloan, Cameron and Ferris are driving to Chicago for the first time in the Ferrari, there is a brief shot of the Ferrari passing a car on a bridge. Look in the bottom right hand of the screen, a perfect shadow of a person on the road. (Original VHS version, it has been taken out of the recent TV versions).
Visible crew/equipment: At the very end when the credits are rolling but the movie continues, Rooney boards a school bus. When a student hands him a gummy bear, a mike is visible in the upper left of the screen. This was a TV version of the movie.
Continuity mistake: Near the very end, Ferris races home in vain as both Jeanie and his parents beat him home. Ferris is still in the kitchen as we see his parents at the base of the stairs, saying 'Let's go check on him.' They turn and start up the stairs. The next shot shows Ferris racing up the stairs. Next, we see the parents begin to mount the staircase (this time from a different angle) for a second time.
Continuity mistake: When Ferris Cameron and Sloane are driving into Chicago they're speeding and flying by every car, but in one shot you can see a car pass the Ferrari in the background. It happens soon after they go airborne and you can hear the Ferrari's engine roaring as the other car passes them by.
Continuity mistake: In the shower while Ferris is talking, behind him there is a rack with a wash cloth on it. They show a close up of Ferris picking up the squirting shower head off of the same rack, but the shower head was not there before the close up.
Factual error: When Cameron melts down and starts kicking the 1961 Ferrari 250 GT California Spyder, he dents the front bumper. There is no way a human being could dent a pressed-steel, chromium-plated bumper by kicking it.
Visible crew/equipment: In the scene where Ed Rooney first goes to the house to search for Ferris, you see a gold colour pot and a reflection of a crew member in it.
Visible crew/equipment: When Ferris and Cameron are in the garage for the first time inspecting the Ferrari, Ferris is shown talking. Shadows are cast on the hood of the car and you can see the shadow of the boom mic picking up his lines.
Continuity mistake: In the opening scene where Ferris is seen lying in bed he is facing his bedroom door. His mother moves him onto his back. When his sister comes into the room, there is one shot of him magically on his side again. In the next shot when he says, "Jeanie!" he has returned to his back almost instantly.
Continuity mistake: In the beginning of the movie when Ferris is laying in bed, and his parents are saying bye to him, the position of Ferris' blanket changes from the close up shots to the far away shots.
Continuity mistake: When Ferris is playing the song on the synthesizer, at first he is using one hand and facing sideways. Cut to another shot and he's using both hands and facing forwards.
Continuity mistake: At the stock exchange the positioning of Cameron's arms go from being on a chair to in his lap to on the chair in a split second.
Continuity mistake: When Rooney is at the Bueller house, he slips off the water spout into mud. His shoe is stuck in the mud when he pulls his foot out. Yet, there is no mud on his calf, which was also in the mud.
Continuity mistake: In the first scene of the movie where Ferris is trying to convince his parents and his sister that he is sick, his left hand changes position several times from shot to shot, going from under the pillow, to next to the pillow, to under the blanket.
Continuity mistake: When the flower deliveryman goes to leave the Bueller house, he toots the horn before speeding off after Rooney flips him the bird. It then cuts to a wide shot of the front of the house and the van is gone. We never hear the van's tires clearing the bump between the driveway and the road, and the van would've had to be going excessively fast to have cleared the driveway in the time between hearing it set off and the wide shot.
Continuity mistake: If you look closely every time a clock is shown you can tell they do not match up. The times match up at the beginning but then proceed to jump back and forth throughout the movie.
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.