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.
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.
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.
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.
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.
Answer: It's an old insult, somewhat equivalent to 'buzz off'.
Brian Katcher