In the restroom stall Jackson's mouth and chin are covered in blood but when Derek pulls him out of the stall his face is clean.
When Allison pulls her funeral dress out of her locker a mirror is on the inside of the door. After Scott interrupts her it's gone.
After Allison pulls out her funeral dress from her locker a mirror is seen on the inside of her locker door. After Scott interrupts her it is gone.
The back doors of police cars don't open from the inside.