Southern Comfort ? Oxygen ? Eigo? (spoilers)

Isn't there a fairly fatal flaw in this plot (I think there was the very same one in Fantastic Voyage as well)...

Assuming that Tuck and the ship are miniaturised by being shrunk, doesn't that mean all their molecules have been shrunk as well ?

Doesn't that then mean that the air and rations Tuck was able to consume would have to also be shrunk ? Otherwise, how could his teeny-tiny body interact with regular-sized molecules ?

So:

1) How can Tuck drink the Southern Comfort that Jack pours down his throat ?

2) How could Jack have breathed the air he was trying for, before he was finally ejected from Jack's body by Jack's sneeze ? (In Fantastic Voyage, they did collect oxygen from the body's lungs, and breathe it. Can't see how, though.)

3) What happened to Eigo's body and his one-man sub ? Jack's body couldn't have digested the body, for the same reason of the incompatible size of molecules, and couldn't have digested the sub at all. Did they just keep floating around his innards forever ?


I know, it's just a movie, blah blah blah, but I find it hard to overlook parts of a plot that just don't make any kind of sense.
Isn't this all a bit of a clunker in the storyline ?