When a rock is thrown through the library window with a note attached, Buffy catches it, removes the note and sets the rock on the table to her left. The view cuts away for a moment, and when it cuts back, Buffy has the rock in her lap and sets it on the table to her left a second time.
Early in the episode, Joyce is shown driving Buffy to school. Buffy is shown wearing a lacy pink tank top and dark brown pants, with her hair. At school that same day, she is show wearing high-waisted green pants and a white tank top with her hair down. Later in the episode, after at least a day has passed, she is showing wearing the pink pants, brown shirt, hair up combo again.
The goof item below may give away important plot points.
When the sacrifices (Willow, Rupert, Cordelia and Jenny) are moved into position over the Master's bones, Giles's hands brush the ribcage; but then when Buffy attacks the vampires standing around the bones, the sacrifices are not in view.