Continuity mistake: When the Swamp thing goes to destroy one of the trucks chasing Cable, the trucks used are chevy blazers but the one he wrecks is a International scout.
Continuity mistake: At the end of the film Cabel gets stabbed in the right side of her décolletage, and she bleeds all over her evening gown, as you would. Swamp Thing very kindly heals the wound. Apparently he also has the power of magic dry-cleaning too, because the blood disappears from Cabel's dress.
Continuity mistake: When Bruno drinks the formula he shrinks and so does his clothes.