Deliberate mistake: Elizabeth Shue uses a drawer handle as an electromagnet. OK if it's really a magnetic material but lab furniture is generally made of aluminium or stainless steel which is not. There is no way that they would use an iron handle in a potentially wet, and hence corrosive, environment such as a freezer.
Deliberate mistake: When Sebastian goes to his employer's house to kill him, the man is standing by his pool smoking a cigarette. When the boss blows smoke in Sebastian's direction, Sebastian appears and scares him. Since Sebastian is invisible you shouldn't be able to see his pupils, only an outline of his eyeballs, but you can see the pupils.