Visible crew/equipment: As the Doctor is watching Will emerge from the priest-hole, look over his shoulder at the far corner. Someone or something appears to be moving in the shadows there.

Revealing: When the crack in the wall breaks open, the wall wobbles rather obviously.

Other: What happens to Tegan's bag when the plague victim transforms into the cavalier? It doesn't appear to be left behind, even when the cavalier later vanishes.