And the contortions that ever and anon conpulsvulsed & deformed his un-human features.
This addition to the Thomas copy associates the creature with the "un-human," an early indication of revisions in 1831 that will make the Creature more monstrous and less compellingly human than he had been in the 1818 original.
Most of the night she spent here watching; towards morning she believed that she slept for a few minutes; some steps disturbed her, and she awoke. It was dawn,
In this 1831 addition, Justine's testimony mentions the sound of "some steps" disturbing her as she waited out the night in the barn. This may be another reference to the creature, as with Victor's near slip with Ernest.
the shape of a man, but apparently of gigantic stature
The first sighting of the Creature in the Arctic, which shortly precedes the appearance of Victor. His "gigantic stature" will later be revealed as a height of about eight feet tall. This seemingly minor dimension of the Creature's power can be appreciated when we think about how few giants or outsized human figures appear in modern realism since the mid-18th century. On this point, see Mark McGurl, GIANTS essay