The tobacco that Richard spews all over the cake disappears in a later shot.
When Richard first goes into the classroom, he puts holes in the floors and walls. In the next scene, they're not there.
When Mr. Clark first talks to the principal in the hallway, Victoria can be seen putting a piece of paper on a wall. Her arms, and the paper, jump about between shots.
During Clark's English lesson, the word "will" mysteriously appears in the sentence.
The Corvette in the chicken run changes from a Corvette when seen in close-up, to another convertible during the race itself.
It would be impossible to steal a car that is flanked by two other cars and backed by a brick wall without its owner (who stood before the car) knowing it.
Obviously, chains will do little to prevent auto theft.
During the climax in Mr. A's restaurant, Griff McReynolds asks aloud, "If X is 17 plus the square root of 4 minus 6, what's X?", to which Natalie Thompson replies, "13". While 13 is a correct answer, it's not the only correct answer. The square root of 4 could be +2, but it could also be -2. So X is technically equal to 9 or 13.
The transit bus used throughout the movie was the same bus used from the 1994 movie Speed but with the transit name and the first digit of the fleet number 2525 removed from the front, back, and sides of the bus to appear as 525. However, the full fleet number 2525 can still be seen on the roof of the bus when it stops. Also, remnants of the first digit can still be seen on the front of the bus.
Richard hands the DJ a "one-only pressing", yet it has commercially-made labels, indicating a commercial pressing.
When the security guard checks students for weapons in the beginning.
When Mr. Clark asks the question, "Who was the first President of the U.S. to appear on television?", he says that the correct answer is "Eisenhower"; the first president to appear on television was Franklin Roosevelt at the 1939 World's Fair in New York City.