In the fight scene in Millie's house The Butcher headbutts Millie in the face causing her nose to bleed, but just seconds later the blood is already dry on her face. If her nose was bleeding it would not dry so quickly. Then a minute later the dry blood pattern on her face changes.
At 3:58 a bottle of "Montrachet" wine is visible, as it falls down, red wine is spilled. Montrachet is an appellation ("AOC") for white wine, Chardonnay only.
The Aztec knife had Spanish writing. An actual Aztec knife would have been engraved with Nahuatl or another language of the Aztec empire.
The cryogenic chamber is shown lowering the body temperature of a human female from 98.6F to -300F in a matter of minutes. The amount of energy required to actually do this would greatly exceed any commercial power supply and black out the entire school. And this doesn't even address the absolutely inconceivable concept that a high school locker room would have such a device, and leave it with no security lock-outs to prevent teenagers from doing something utterly stupid.
The Aztec had no concept of twenty four hours, only of the general time of day in relation to the sun and other celestial bodies.
Josh has a custom California license plate saying "HEY BTCH". California would never allow anything so obviously resembling a vulgar word on a plate.
When the Butcher, as Millie, stabs the knife through the bedroom door, the blade is upside down.
Twice, cops are shown firing their guns in the air. The second time, they are indoors. No police department would ever train or permit their officers to do this.