When Buffy breaks the glass during her talk with Giles, it is almost halfway full, but just as she breaks it, there is barely any liquid left.
When Buffy takes the rifle from the human hunter, she pumps it, supposedly chambering a round. Moments later, while in the cabin with Cordy, she pumps it again. No round is ejected, revealing the weapon is actually unloaded.
At the library when Buffy is discussing the strengths and weaknesses of her opponents, the bandage covering her broken hand is clearly visible under her sleeve.