Related to Ant Man movie -

As we all know Hollywood make movies which are most valid to science but after watching Ant Man, here concept of reducing interatomic spaces between atoms is used to shrink any human to size of an ant. My only question is that on reducing the size the matter contained in the body shout remain same (Law of Conservation of Mass & Energy) but here Ant Man weight gets equivalent to ant. Sois it a movie flaw or I'm missing something ?